Do they still make Persona? I heard that there were so many pregnancies amongst users that women who wanted to get pregnant were using it it pinpoint their most fertile times.
Have you tried a diapraghm? It sounds grim. I had the smallest size and it was still quite startlingly large. You think it's not going to go in there. It's embarrassing being taught how to insert it, but not terrible. I got so good at it that she asked if some students could come in to watch and feel. Because I am very competitive and a sucker for praise I agreed though after the fifth person wanted to watch and have a poke I said I'd had enough.
Putting it in in the field is difficult when you've had a few drinks - it pings around the bathroom and by the time you've got it in, you might have gone off the idea - so I'd recommend putting it in a few hours ahead because the spermicidal jelly will still be active. You just have to squirt up a bit more to be on the safe side when you want to have sex.
It can't be felt by you or your partner if it's in right. In fact, that's good because if he can feel it, it's not in right and you should stop.
I had one ages ago when I couldn't take the pill because of other drugs. I was a bit depressed because the reliability is lower than the pill and it can be a passion killer. But I learned and I didn't get pregnant. I was diligent with cleaning, storage and checking for holes and very liberal with the spermicidal jelly though.
DH said spermicide makes your tongue go numb that that wasn't a problem for me 
The nurse also recommended them during periods like a forerunner of the Mooncup. That works too.