Keeping the baby baby fat ?

Phontella • 24
I'm 24 I'm 5'7 and my weight stays between 127-130lbs I can eat anything I want and never gain weight I missed my period last month first test was a BfN I think I took it to early. ..I'm taking another one in a couple of dAys anyway. ..if I'm pregnant how do I keep the weight especially my boobs I wear a 34b and when I get pregnant I want to keep all the weight just lose the tummy. My question is how do I keep the weight. ..lol I think I'm the only one who want to keep the baby fat lol