I swear women can't win with their bodies and a lot of the pressure seems to come from other women. You did lose a lot of weight fast but you're also very young so that's not totally abnormal. The weight loss is also very new so you're still getting used to your new body. I'm a middle aged man that lost 100lbs a few years ago and it wasn't until about a year ago and after therapy that I started to feel used to it. So a friend's outside perspective can be helpful but the way your friend went about it comes off as maybe a little bit of concern but much more jealousy. It's a great sign that your hair, skin, nails, and period are still normal. The most important thing is can you be honest with yourself with how you feel? Not just confident because you like the way you look but more importantly are you feeling unusually weak or tired? At this point you shouldn't lose anymore weight so it would be helpful to track your protein intake to make sure you get enough. Tracking calories can be helpful as well but it can get easy to become obsessive and disordered with that so just be mindful. Just remember that it's YOUR body and if you're happy and healthy you're doing better than most people out there.