How to be less Insecure about myself ?

I am insecure about my body , my scars , my personality ,ect... I stress and stress about my weight I am a 14 year old girl who weighs 110 at 5'7 . I was called too skinny once and that has made me even more insecure I restrict now to one or two meals a day that are small. I feel so fat and I can't eat in front of people becuase I am afraid that they are watching me eat . I am a really shy person so every thing I do feels wrong for some reason . I am mostly insecure about my scars I have Been self harming for about 6 to 5 months and the scars won't go away . I haven't stopped yet but everyone looks at me like I am a psyco having scars help:(