Birth control loose and gain!

Hello everyone! I'm a FTM of a 9month old and Im going on birth control for the first time I'm 26 and during my pregnancy and after I lost weight to the point that I haven't gained anything. My doctor says I need to gain at least 30 pounds so I go back to being on a healthy weight for my body. Right now I'm too skinny and that's not good for me. I'm wondering for those who took pills with hormones or any other birth control did you loose or gain weight?

I don't mind the gaining but loosing is a big no no for me. I've heard so many things about this with birth control loosing and gaining weight that I'm scared I'm going to get thinner and that scares me.

For those wondering BF didn't cause me to loose weight it didnthave anything to do with my weight for those who say anything on that. Just an FYI.