Help !!

Ok so I'm 16 and I bought my first cup with only my sister knowing. I started my period 2 days ago and yesterday I tried inserting the cup. I COULD NOT get it in haha so i gave up. I didnt want to give up completely so tonight I tried again. I got in the shower and after about 30 minutes I got it open and it was all good ! Then I realized that the stem was too long for me, even though it was so small. Whenever I moved around it just hurt. So, I took it out after about 10 minutes and I cut almost all of the stem off. I tried inserting it again, but it wouldn't go in. I got back in the shower to see if it would work. I'm able to get it in, but it just WONT open up. I have been using the punch down fold and that is what worked the first time. with the 7 fold, it just comes right back out and the c fold is too big for me. I try twisting it or pulling and squatting but it just wont open. It was so nice having it In me and I didnt have to worry about bleeding everywhere. anyone know what I can do to get it open ??

Sorry I know this is alot 😭😭 I am just so desperate for it to work.