Menstrual Cups - Divacup, Mooncup, Instead, Lunette, Miacup

Hey, I've been lurking for a good few months now.

I've been reading a bunch of first time use posts and all about the cups. I finally settled on getting a Classic MeLuna - small and medium. I tried for the past couple of nights to get it inserted while in the shower, and I'm having a bunch of troubles, and wondering if ladies had any extra advice.

A little background info: I'm 27, and rarely used tampons in the past (probably once or twice only), I'm pretty unfamiliar with my anatomy. No children, not a virgin. I tried to find my cervix, but I'm not really sure what I'm looking for. I think it's about 5.5cm in? I tried to Google an "average height" sort of thing, but all I got were pregnancy heights.

Anyway, I tried the C-fold and 7-fold, but they're too big and I can't get it in. The punch-down-fold is the only other one I've tried, and I can get it in, but I can't for the life of me get it to pop open. I run my finger around the bottom and I feel the dimple of the fold there..I've made sure the air-hole is where the fold is. I've tried to twist it..and nothing.
I've even tried some lube to get it in there, but it's just not working? do I just wait until my period and try again?
I feel like I'm just tensing up every time I move the cup near it. I haven't even tried to use the medium if I'm having this much trouble with the small.
Also, on the side - I keep pinching myself when I try to run my finger along the edge/front/back of the cup once it's in to check, is that normal??

I didn't see a post about this so I made an account just to write one. I'm 17, virgin, and have actually never been able to touch my cervix (haven't tried during menstruation though). I got the Divacup mostly because I had no idea there were so many other kinds, and even though this is my first time actually using it it's doing pretty well. Only had a few leaks but that's because of newbie insertion and the fact that my flow is really heavy on the first day.

I can put it in fairly quickly and with no problems, I can even spin it around (wheeee). But when I try to remove it, pinching the base doesn't work to remove the suction. I read some of the other posts on here talking about how the Divacup specifically has really small holes, and I might try to address that, but... I try pinching the base and squishing it to one side, and I basically have to stick a finger all the way up to the rim and let air in so that I can pull the thing out (which makes some really weird noises, mind you), and while it doesn't hurt to remove it as much as it did, by the time I've gotten the damn thing out all the blood was just squished out of it and the whole endeavor was made pointless. I'm just wondering how you're supposed to take it out and keep all the blood in. I've felt that suction pain once, and am terrified of that happening again. I don't want to get another kind of cup, I already have two of the divacups and I live outside of the US so it's not exactly easy to buy a new one.

I also read somewhere about someone taking it out in the shower and throwing the blood on the walls like a serial killer. Knowing me, I'd probably just use it to draw a pentagram. TMI maybe, but this is a forum about menstrual cups, that line's all but gone.