Do not feel troubled brother. Allah is the One who makes these easy. I ask that he make this of benefit for you and He always guide you and me to good.
I'm no scholar but the best definition I can give off the top of "Acts of worship" is an action by which the person doing it seeks nearness to Allah or seeks His Pleasure and reward. That's not a legal definition but that is the best I can come up with.
It is good that you support not adding unnecessary extras. Celebrating the Prophet (sal Allahu alayhi wa salim) birthday is a very good example.
But see the thing is by not adding extras, not only are we maintaining tradition but we are fulfilling an obligation of Islam.
Allah said "...This day have I perfected your religion for you, completed My favour upon you, and have chosen for you Islam as your religion..." 5:03
So Allah completed Islam so it doesn't need anything added onto it and it is already perfect so no one can come up with anything to improve the religion. And Allah does not want anyone to add to it.
You are right, personal interpretation and action are vital. But like all things only if done within the proper guidelines.
Ex: Providing for your family is a good thing but not if you do it by robbing banks.
Personal interpretation and action are the same way. They are good only if they are in accordance with what Allah commanded in the Quran and how the Prophet (sal Allahu alayhi wa salim explained it.
But brother, it is very important that you begin to ask Allah to help you, to guide you and to make things clear for you. Study the Quran and start to learn about the life of the Prophet Muhammad (sal Allahu alayhi wa salim) because honestly, one cannot properly understand Islam unless they look to his example. And that is how Allah wanted it.
Indeed you have in the Messenger of Allah a beautiful pattern (of conduct) for any one whose hope is in Allah and the Final Day, and who engages much in the Praise of Allah. 33:21
"SAY! (to them) If you truly love Allah, then follow me. Allah will love you and forgive your sins: For Allah is Oft-Forgiving, Most Merciful." 3:31
So the best example possible is Prophet Muhammad (sal Allahu alayhi wa salim) and Allah commanded him to tell us that if we truly love Allah then we will follow him.
But now think about this; if his example was not recorded in some way, how could later generations follow him? Allah made sure that his life, through the hadith, was recorded. Hadith really is history. But the history of Prophet Muhammad's (Peace and blessings be upon him) life. The early muslims memorized what he said and did, wrote it down (which many don't know but they did) and passed it on generation after generation.
Is every single hadith authentic? NO! But that's why muslims study them, scrutinize them and meticulously dissect them so that when a scholar of hadith verifies it you can be sure that the Prophet (peace and blessing be upon him) really said it.
Authors of books, like Bukharee and Muslim, so meticulously selected the hadith that they included that every hadith scholar in the world acknowledged that the hadith they choose all were definetly said by the Prophet (sal Allahu alayhi wa salim)
So believing in the authenticity of hadiths that are proven to be authentic is a must. If one of the known schlars like Bukharee, Muslim, Imaam Ahmad or the like (and read their bios to find out who they were) say a hadith is authentic then it is the same as if a Doctor tells you that you have to stop eating fat or you will get a heart attack.
You can either listen and live and Allah will reward you for saving your life, or you can say "I don't trust this hadith! (Hadith linguistically is often used to refer to a saying or speech)" and then eat a Hardees Monster Burger and die.
BUT you'll have to answer to Allah as to why you did not listen to the Doctor.
I know it is hard to have to trust someone with something so important but the one whom you really must trust is Allah. Ask Him to guide you to the truth and be open to His guidance.
If you start to understand the importance of hadith then you will see that personal interpretation changes with knowledge.
Do you have a Quran brother?
Look in it. You will not find a single verse that explicitly states how many times a day we must pray. Or how to pray for that matter.
Allah tells us to cut off the hand of the thief. But how does He define theif? If you steal a piece of lint from my pocket does that count?
All of these details Allah omits from the Quran because He wants you to turn to Prophet Muhammad (sal Allahu alayhi wa salim). He sent him as an example and He made understanding Islam dependent upon referring to His Messenger.
Upon doing so, then you will begin to get a different interpretation. Remember, what is important is not just a personal interpretation but the right one.
As far as adding things in the religion, that is something muslims should never do.
Imaam Ash Shaafa'ee Musnad reports the Prophet saying "There is nothing that will draw you closer to Allah and farther from the Hellfire except that I commanded you to do it. And there is nothing that will take you farther from Allah and closer to the fire except that I warned you against it.
Would you like to know something scary?
Remember that Jesus and Moses (peace be upon them both) were muslims. They brought their people nothing but the Truth from Allah.
So how did Christianity and Judaism become what it is today.
INNOVATION.
Someone yelled "Wouldn't it be great if we celebrated Jesus' birthday to show how much we love the Messenger of Allah?
A year later it was "Jesus day is so great my parents bought me all these great presents!"
20 years later
"Father why do we celebrate Jesus Day."
"He's a Messenger of God son?"
50 years later
"Father why do we celebrate Jesus Day."
"Because He's a Messenger. And his message to the world 'I'm God son'"
And thus...Satan entraped them.
A small innovation today becomes something horrendous tomorrow. Allah gave us a religion that does not need extras.
Everyone must do ijtihad. When you read this, you are doing itjtihad insha'allah. Meaning you are exerting your utmost, in this case to understand what I am saying.
Now, you should do the same with the Quran. Exert your utmost to try to understand it and develop an interpretation.
But realize, that your interpretation will be limited by how much knowledge you have and how valid and correct your knowledge is.
Valid and correct knowledge is found in the life and example of the Prophet Muhammad (sal Allahu alayhi wa salim)
So yes, you will still interpret from your perspective. But you must know that without all the relevant information and knowing how to apply it your interpretation will be limited and perhaps flawed.
So if you act upon that knowledge your action will be wrong and Allah will not accept it.
I hope you don't think I'm mad at you or anything. It is difficult. So much in our life is "Everybody's right, nobodies wrong" type feel good stuff. Most of us were Christian before we became Muslim.
Some Christians let poisonous snakes bite them and they say they do it to prove their trust in God.
Some women claim they praise God by getting "God rocks!" tattoed on both their boobs and then piercing their clit with a ring that has a cross hanging from it.
I don't say that to be mean or funny, but seriously. Does attempting suicide and exposing your privates to strangers even sound like something God wants someeone to do?
When someone has a job does their boss just let them work anyway they want or are there rules?
Allah made rules on how he wanted us to worship Him and the way to learn them is to learn how Prophet Muhammad (peace and blessings be upon him) worshipped Him.
If you want more info on the life of Prophet Muhammad (sal Allahu alayhi wa salim) and about why you should trust hadith and some information on how his life was preserved I will try to provide it for you insha'allah.
Rejoice that Allah favored us with a perfect way of life:)
I hope I helped. If you have any questions or comments hit me back.
May Allah Guide me and you. Ameen.