Why am I not loosing weight

I’m 18, I’m not overweight or anything but I wanted to loose some pounds to feel better about myself. I’ve been calorie counting for almost 3 weeks now. I’m tall (5’9) and when using my calorie counting app it says to maintain my weight I need 3200 Cals a day. I’ve been having under 2000! Shouldn’t I technically be loosing weight from doing this?? Am I doing something wrong? What works for u??