Ive come to believe that a lot of what people see in you, is what you portray. dont let them see your self conscience. show yourself to be proud of what you look like and even laugh along if you can saying "ha yeah i know ive got a big head" dont let it get you down. Its just a problem like being short or skinny or pale or w.e you can think of. Having a big head is no different. Your still 17 and im still 18, and i believe as we grow older our faces will loose any lingering baby fat.
Just think theres someone out there with a bigger head than you and probably someone witha tiny head! maybe if you get into a fight or something you can head butt someone into submission? its pretty hard to think of the advantages, but if theres people making fun of you, you can label them as douches. Im terrible at giving advice, but thats all ive really got.
be proud and confident,
let the insults go and ignore em
ignore jerks and think, what makes their opinion matter anyways?