I'd talk to your doc if you're concerned. You don't want to lose too much. I was 131 pre pregnancy. Now I'm 145 two weeks until my due date. I'm a bit worried about how much I will lose. I don't know your build or body structure but 120 sounds like a healthy weight to be at and you just want to be sure you're getting the nutrients you need to be healthy. My sis weighs 100 and she's 21 but her build makes it a healthy weight.

I had to stop breastfeeding when my girls were a little over a month old my milk dried up but I'm still loosing mad weight... @chhaya

I'd talk to your doctor. If you're breast feeding it'll make your weight loss even more. Just to make sure you're getting all the nutrients and such you need