Please help

so I’m on birth control but when I got to my placebo pills I didn’t get my period. I’ve tried missing a few pills on purpose as well to see if I would bleed and I did not. Which normally doesn’t happen. I’ve been on birth control for about a year now too.

I gained a lot of weight (on purpose) over the last few months if that could affect it. (About 25 pounds since January)

I’ve also taken 3 pregnancy tests-all negative.

What scares me is that my stomach is sticking out in a balloon shape. It’s very round and it doesn’t look like just “fat”.

I just want some opinions.