Just reporting back on what I think is my fourth cycle with a cup.
Firstly, I had a mooncup UK (stem removed) and found it both a challenge to remove and deal with inside of me. It felt really horribly uncomfortable, like there was bad pressure on my insides. It was difficult (though not impossible) to remove squatting in the shower.
I bought a small lunette, and found it immediately less of an irritation than the mooncup. I was able to leave the stem attached, and to me, it felt a softer cup in texture and...poppyness...heh. However, I still had that sick, weird, wrong feeling while it was in. I could sleep in it, but couldn't keep it in for more than an hour or so during the day. Removal still very difficult, but got better each time. It (like the mooncup) would travel /very/ far inside of me (only just within reach of my fingers). Though sexually active, I find I am fairly small, and I have weak kegels (working on it though :P) which makes bearing down pretty difficult and not as much of a help as it should be. I also have never been able to reach the end of my vagina, nor my cervix (which is why I didn't think the 'weird' feeling was cervix related, but it could be), so keeping the stem on is a help. Keep at it, those who have problems.
Today, about 30 mins ago, I inserted the lunette using the origami fold, as opposed to the punchdown I'd used every other time. I took care to insert so the bell was just inside of me. I felt no characteristic 'pop,' but I believe it's at least mostly open. It has since traveled up inside me to the point where the stem is almost completely inside (maybe two ridgy bits out, other lunette users will know what I mean).
I can't tell you how much of a surprise trying the origami fold as opposed to the punchdown was! It DOESN'T FEEL WEIRD for the first time ever, and I finally think I'm seeing light at the end of the learning tunnel. I don't know whether it's because it's sitting lower, or that it didn't push against my insides so much when it opened.
I am not 100% sure it's completely open, though, and am using cloth pads for backup. I plan to leave it in this way until tonight (about 5 or 6 hours) and hopefully all will be good by then.
Thankyou to everyone who's helped me, I hope this will keep working for me :) Just a lesson to those who have only tried one fold: try another! Sit there at the computer playing with your cup until you can do it easily. It makes all the difference :)