Worse cramps with my cup?

Hello! I've been lurking this community for a long time, since I decided to get my cup, about four years ago. This is my first time posting, I tried searching for someone with similar problems, but couldn't find it.

I had been using pads, until I tried a tampon, and decided that I loved how less messy it was, but absolutely hated they way it felt coming out. So after a lot of research, I got an Inciclo cup (I guess it used to be called Misscup before), since I can get it easily on Brazil.

I used to have really bad cramps, and I had hoped a cup would help with them, but it didn't make any difference. I still loved it, and had absolutely no problem with it, I just had to cut the stem.

However, about two years later, I decided to get a Mirena IUD, and after a hellish week of cramps and spotting my periods stopped for a while, and I retired my cup. But they came back, much lighter and much less painful, and not that frequent. I spoke to my doctor, and she says that's ok.

I tried to go back to using my menstrual cup, but I found that when I wear it, my cramps get so much worse, even after wearing them for a long time.

My cervix is pretty high up, and I have to make an effort to touch it with my longest finger. My cup sits around it perfectly, and it feels like all of it is inside the cup (I think that's what it means to "O" around the cervix?). When I take it out, however, it feels like it has changed shape, like it got longer inside the cup, like it has been sucked in.

My theory is that the rim diameter is too small for my cervix, so instead of just sitting inside the cup, it gets squeezed in there, and that's why it hurts. Can that happen? This also happened before I got my IUD, so I'm guessing that my cramps were already so bad that they couldn't get much worse.

 I wanted to go back to using a cup, but every time I try it I end up in a lot of pain. I've been looking into buying a wider cup, but could that be the problem? Should I get a less wide cup instead?

Thanks in advance!