Mom making me feel bad about my PP body.

Okay, I am 15, 16 tomorrow, and I had my little boy 3 weeks ago tomorrow as well. I gained a lot of weight during the pregnancy, I went from 105ish to 170. I ate really healthy and everything when I found out I was pregnant, which wasn't until I was 23 weeks along already. My stomach had a TON of stretch marks because I was such a little girl and I had a 8 pound 4 ounce boy inside of me. Anyways, I walk around my house in my bra a lot, I always have since I was a little kid, but anytime my mom sees my stomach she says its gross and to put that shit away, or start working out or something, I don't know if it's hormones or something but it really hurts my feeling and makes me feel bad about myself..I can't help my stomach is flabby and gross..but hey, atleast I have a beautiful baby boy from it...