Menstrual cup issues

🍀Karma🍀 • Small town woman and mother of 3. Pagan Witch. Bi Poly.

I recently started using one. I have issues peeing with it in, like it's harder to pee and it feels like I have to pee more.

I got a large because I've had 3 kids and am 29.

Am I not using it correctly or should I get the smaller size?

Any information would be appreciated, thanks.