Menstrual Cup frustration

Guys, I need advice. So I purchased a menstrual cup a few months ago and have been trying to insert it ever since. Pads and tampons aren't working for me considering I have endometriosis and fill up a tampon in 45 minutes. So I really need this to work. Every time I try to insert it, it pops out and I end up frustrated and in pain. I'm a virgin so at first, I thought maybe my vaginia wasn't used to anything going up there but I wear tampons with no problem. I ordered the right size cup and everything because I have a low cervix. So would it be weird if I asked my gynecologist for help? Am I doing something wrong? HELP!!!