Is this an eating disorder?

So back in 5th grade I stopped eating as much. I stopped eating breakfast and then lunch. All I had eaten every day was dinner. I am now a sophomore in high school almost junior and I still do this. 

I have body image issues as well with skinniness and waning to be between 110 and 120 lbs at all times. I mostly struggle with my thighs and stomach. I finally got more comfortable with my thighs last year but I’m still self conscious of them. I don’t like my stomach any time I don’t see the line on the side where my abs are to be. 

I used to only eat in front of close friends and family. Now I only eat in front of family. Friends who I felt close with I am afraid to eat around now and I take any chance to skip any food around people I don’t know or who isn’t super close family. I skip food at church, sleepovers if given the chance, people I am dating, friends, school, and I try to eat very little portions if it’s times where I am forced to eat. I feel bad any time I am staying with my father and his family or my friends because I feel as though I do not deserve to be eating their food that they worked hard for. 

it’s become a fear to eat around people who aren’t my close family members such as my great grandfather, mother, brothers, and grandmothers. When staying with my dad I eat little and at night look around the kitchen for small things like fruit. I’m lost on what to do. 

Can someone tell me if this is an eating disorder and what kind it is? If it even is a disorder how do I fix it? I feel more hungry lately but try not to eat so much because it’s most likely due to daily stress. Before I used to eat at least half of a small plate portion wise.

what should I do?