Birth control Norethindrone help!

Mrs. R
I have an 11 week old. I've been taking this birth control for 5 weeks. I had lost 25 of 40 pounds and for 3 weeks have been eating extremely healthy to get the rest of the weight off. I am nursing. Ever since I started taking this I've gained 5 pounds. Has anyone else had this experience? I'm starting to think its the pill bc I have been so strict on eating right. I've also felt more bloated since taking it. Any experiences shared would be appreciated! Thanks!