I have really really low self esteem, how can I make it higher?

Well i'm 13 and in 8 grade so my mom says its just awkward age or something like that. But I can't stand taking pictures or looking in the mirror! It seems like every time I walk into the bathroom at school there is a popular girl that is 200 times prettier. Oh i'm also really short so I always feel short and stubby even though i'm acctually really skinny. I think what bothers me most though is my hair, its a little bit longer than my shoulders and blonde. Is there anything at all that I can do to make me more confident about any of this? Thanks <3