I've been using a Divacup since November. I ordered it on a whim when tampons I had flushed ended up clogging the sewer line, which resulted in a not too happy landlord. Point being, I didn't really research brands/sizes/etc of cups before ordering the Diva (it was about the only one I had really heard of in the US). I am 25, sexually active, no kids, and have the smaller size.
I don't have any trouble inserting it or anything, but I find that it often leaks when I'm sitting down or at night. I'll take it out only to find that there's hardly anything in it (maybe 1/3 full). I can feel that my cervix is centered over the cup, so I know that isn't my problem. I wonder if my cervix is just taking up too much room in the cup? Or is the cup too soft and getting a little bent when I'm sitting (driving, etc), or sleeping? (My mom has said she was told she has a tilted uterus, so I suppose I may too, but I have no idea if so and if that would have any effect).
I'm kind of shopping around for a new cup now, but I'm not quite sure what to look for. I have a somewhat heavy flow, so I was kind of thinking a large Lunette or large Meluna (I admit to being a sucker for the colors)... But I don't know if my problem is that I need a bigger cup, a stiffer cup, a shorter cup, etc. I've browsed around looking for similar posts and find that the common causes are ones I've already kind of ruled out (cervix out of the cup, cup not opening, etc). Sooo, anyone have any thoughts or suggestions as to why I'm having the leaking issue? Or opinions on what cup might work better for me?