should I get checked for an ed?

I'm sorry for the long post.

I have always been underweight ever since I was a child but recently I've been getting more and more particular about my food. Before moving to college I did not eat very much simply because I wasn't hungry but now I find myself going out of my way to not eat and counting the calories in everything. I try to eat under 1,000 calories a day and im pretty good at doing that because I eat one meal a day if that. But I found a diet that requires you to eat less than 500 calories every day and I wonder if I would lose weight and get a flat stomach like I want if I tried that.

It's really starting to spiral out of control for me because I used to not think about what I eat even though I ate very little but now I feel bad about eating things that have a high calorie count. Ive only eaten two cookies today but I felt terrible about it because they were 230 calories each and that took up almost my entire 500. I'm definitely not over weight but I just don't feel like I'm happy with where my body is at I feel like I am not as skinny as I should be. I've tried exercising but it's hard for me to stay consistent with it as I also struggle with depression. It's much easier and cheaper for me to not eat than to go exercise or make the effort to cook healthy meals.

I don't know if the way I eat is an eating disorder of the early signs of it because this is relatively new for me but I have always been someone who undereats. Especially when I'm sad I completely lose my appetite and have gone over two days without eating I already struggle with self harm and depressive episodes and other physical conditions so the idea that I may start having an eating disorder on top of that is really stressing me out. I don't know if I should try and seek help for these behaviors or if this is something that's normal that most people go through. I would really appreciate any feedback.