I have been using a UK Mooncup Size B for almost six months now and I have got over the initial challenges of inserting/removing for the most part but I'm still having problems with leaking on my heavy days (quite heavy flow, some 'gushing'). I have been reading all the really helpful posts on here but I'm still not sure what's going wrong for me as I am inserting, helping it pop open using my fingers, giving it a twist and small tug to make sure it's in place and cleaning the holes each time I empty it but somehow it still leaks heavily without catching much blood if I'm walking around or being particularly active; it also leaks badly at night too. It's definitely not always full when this happens, nor is it residual slobber. On lighter days, it works fine and the suction is definitely in place. I'm wondering if it could be the cup I'm using? Does it matter that I have cut away the whole of the stem (it always slips slightly sideways once inside)? Is the problem with my positioning? I've tried keeping it low and getting it as high as possible, but neither seems to help.
Extra info: I'm 29, I don't have children, on and off sexually active, I have vaginismus and vulvodynia so I definitely do not want a stiffer cup- in fact, quite keen on trying a softer cup after reading posts on this site, but I also need a cup that I can cut the whole stem off because stem irritation is a major problem for me. My cervix is 6-8cm high on heavy days. I'm not worried about the cup slipping up inside as this happens a lot already and I'm quite confident about using my muscles to wiggle it back down. I did think about a bigger/wider cup for heavier days but I already feel my mooncup pressing against my bladder (makes me want to pee all the time!) and it sometimes causes some lower abdominal cramps too - although after reading posts on here I'm not sure if this is because of the firmness of the cup rather than the size.
Basically, help! I really don't want to give up on menstrual cups but I need something I can rely on for heavy days and get in/out without too much pain.