I've used a small diva for three cycles, and I love it, even though it's not quite working like I'd have hoped, heh!
my first issue was discomfort, so I flipped it inside out - whatever, not a problem, it seems to decrease capacity to the point where I need to empty it every hour or two on heavy days, but it'll do. the issue I can't get past, though, is the constant, steady leakage. the flow is greatly reduced, it's catching MOST of it, but a lot still leaks out at a steady pace. it just doesn't feel like I ever get suction with it, like it can't pop open all the way. with a good bit of discomfort I can swirl my finger around the cup and sometimes I feel air move a little bit, but it feels like my finger is resting inside a dent in the side of the cup and I'm just swirling the dent around :P I've tried getting it to open closer to the entrance, and then pushing it in and back/down, which seems like it should help because it situates it in a comfortable place, but it unfortunately doesn't.
it's definitely not residual blood in the canal, because it will leak constantly for hours, even when the cup's like, less than a third full. it just doesn't feel like there's enough room internally for it to open, but at the same time there's obviously blood leaking past it. I'm guessing cause it's due to that dent allowing constant blood flow.
so I'm wondering if a ladycup would be a better fit for me, cause I've heard they suction like DAMN (even if it is a little intimidating). but my flow can be incredibly heavy, so I'm sort of leaning toward trying a large. any advice would be greatly appreciated :) and oh, wasn't there a picture floating around, a size comparison between an inside out diva and large ladycup somewhere? I was trying to find it but couldn't.
and finally, I also wanted to thank you lasses for the excellent information! I've been lurking since january, and this community was just the handholding I needed to finally buy my cup in february :) (yes, I've only used it three times since february, my cycle has always been very irregular - more like a month and a half in between.)
anyway, thanks in advance!
EDIT: I cannot believe I forgot this. the diva DOES suction HARD initially, but there's no air in the thing so it's not at all popped, and if I leave it like that, unpopped, blood just leaks around it, and it hurts a little. it suctions almost totally flattened, and I have to stick my finger in and try to break the seal so I can fill it with a little bit of air. there's really no winning here :P
EDIT 2: does it NEED to be filled with air/popped? it almost seems like the air would just be displaced as it filled with blood, thereby _causing_ the air and (probably some blood) to leak... this is hard to explain. I feel like it probably can't be "popped" and rounded without being air filled, but if I break the initial suction, I can't get it suctioned again... but either way, it'll leak.
EDIT 3: just wanted to collectively thank everyone who's been trying to help me! I really appreciate it :D