First of all, you are only 16 and a lot of stuff will change soon.

Second, my girlfriend is 148 and she's not fat at all, trust me and she's probably just a little taller than you. So you are not fat :)

You have nothing to worry about 5"5 110 sounds damn good.. Dont worry yourself..

Stop obsessing about it--you are quite underweight. If you start losing weight, you are likely to develop an eating disorder, like anorexia or bulimia, and you do not want to go there. Trust me, I know what i'm talking about--i have been struggling with anorexia for years and while i'm physically better (it never goes away completely mentally). The worst thing you can do to yourself is try to lose weight. I'm 5'4" and 115 lb. Now, which is the low end of normal for my height so you do not need to lose weight.

Cin1812 seems to know what she is talking about, you don't want to become annorexic or bulemic, she is right, it is not worth it, it can kill you! Be happy with yourself, even if you gain another 5 to 10 lbs after all it what is on the inside that counts as long as you are a loving caring person, that is the main thing!