I need alot of support & encouragement

I'm BF my baby, & formula feeding during the day. I know I probably dont need any reassurance to think I'm doing the right thing but my boyfriend doesnt seem to support me & it's getting me stressed & irritated. I dont wanna pick a fight with him but he keeps saying how it's going to ruin my body & how I had a better body & boobs before. He sounds so ignorant. & wish I had the support & kind words. Iv been feeling self conscious lately & that hasn't helped. I know he's getting all this from his mom which I'm surprised most woman support BF. She also doesnt seem supportive. Any advice