Weight gain ?

I’ve been on birth control the pill for about 2 years. I got on it to lighten my period which it started too little at a time. Lately my periods have been super light but I also gained alot of weight. Kinda scares me and makes me think I’m pregnant but I’ve taken 2 pregnancy test both came back negative. Could it just be the bc finally working for me and just making me gain weight like it does for other people? Just weird cause I’ve been on it for 2 years already