Please help me decide on a cup!

[mrslevell2b]

I am 24 years old and never given birth. I have Endometriosis and a tilted uterus that tilts back towards my spine. I have a relatively normal cervix length. I currently use the Instead Soft cups. I like them but I dont feel they are secure enough. The amount of firmness to the ring is near perfect but they can pop out with a sneeze easily. I know that the Diva cup is out of the running because it is longer than the length of my vaginal canal. I am wanting to stay under $30 as well. I have a really light flow now due to my Depo Provera but I would want something that could hold a moderate flow to slightly heavy flow.

Cups I have narrowed it down to:
Medium Meluna
Small Lunette
Small FleurCup