Weight gain and the pill?

I started on the pill about three years ago and it didn’t really have any effects on me besides regulating my unpredictable period. I have been struggling with acne since middle school so I decided that I wanted to switch to a different pill just to see if it would help with that. I switched in December (it’s now April) and I have been noticing that my jeans are getting a little too snug, some of them completely too small. I try to brush it off but it’s really ruining my self esteem and a broke college student can’t afford to go buy a bunch of pants to replace the ones I’ve grown out of 😂. Three years ago when I first talked to my doctor about birth control, she told me people gain weight because the pill increases their appetite, but the pill itself doesn’t make you gain weight. However, my appetite and diet have been the same if not better. Is it possible that my doctor was wrong and the new pill is making me gain weight, or am I just coincidentally gaining weight around the same time I switched up my birth control?