I’m 19 and I’m 113 pounds and I’m 5’3.5.

I’ve always loved food and I have a very fast metabolism. once I turned 18 I just haven’t been feeling the need to eat. I used to weigh 125 but I lost so much muscle weight accidentally because I would only have a little food throughout the day. So I just turned 19 and it’s getting worse. I’m never hungry and my stomach becomes full very fast. All i honestly rather do is drink water and smoothies all day.. it doesn’t seem to hurt my stomach as much as food does/make me feel nauseous. I went to the doctor and they thought I was doing this on purpose🙄🤦🏽‍♀️ they thought I was bulimic/anorexic. And yes I have always been skinny but it’s not healthy to be eating very little. If I do eat a normal portion meal (I have to force myself so I don’t lose more weight) that’s all I eat for the day and the rest of the day I’ll be drinking water/juice and a snack like almonds or fruit snack pack. I also don’t get the trigger to tell me I’m hungry I just don’t feel a need to eat like ever anymore?? And I do sit ups and some planking every other day just to keep my core tight for a light exercise but I still don’t get hungry even after a light jog around the block. I literally lost my appetite. 🤦🏽‍♀️does anyone have any input?