I've been using the Diva Cup (Size 1- I'm 24 and have never been pregnant) for six months now, and after a valiant struggle with it, I am ready to go back to tampons and pads. Insertion and removal haven't been huge problems for me for the past few months (although there was a painful learning curve at first :P), and I've finally figured out how to get it to open and how to make it seal. But despite all that, after about an hour of successful wear, it suddenly starts to leak EVERY TIME. I check that it is fully opened (yup), that it is still sealed (yes) and that there are no dents/puckers (none). I've used every fold possible. I've used every insertion position on here and have tried tons of methods for creating a good seal (spinning, stirring, pushing on the walls to let in air, etc.). I've tried keeping it very low and inserting it higher. It doesn't seem to be a size issue, either- the cup is held so firmly in place that it's sometimes a bit of a battle to get it out (yay Kegels).
The one thing I've noticed is that no matter how I insert it, after about an hour of wear (depending on what I'm doing- biking seems to be the worst), the thing gets suctioned all the way up my vag as though my vag were a vacuum cleaner. It still seems to be sealed and fully open, but since my uterus is tilted far to the left, I think that the Diva may be getting suctioned right up next to or past my cervix.
I think the Diva is just not a good fit for my body. But after having read hundreds of posts on here comparing the different brands, I still don't know (given my overactive vacuum cleaner of a vag) if it's a better idea for me to go with a stiffer cup (Lunette), a shorter, differently-shaped cup (Keeper Mooncup), a softer cup (Lady Cup), or to just give up, become a hermit, and sit on a pile of straw throughout my period. Or the next worst thing, use pads :(.
Advice about which cup may be best given my particular problem would be awesome! :)