insecure about my arms. `18 yr old female

I am 18 years old. For as long as I can remember, I have struggled with confidence issues. My reason is the size of my arms. Everyone tells me I am "so pretty" and that my arms are fine, but I am so insecure of them. I don't like to wear sleeveless shirts, or tank tops during the summer. I have tried everything possible, and seem to get some results, but then i fall back to where i was in the beginning when i fail. I lift weights, i do a ton of cardio. Every day I am at the gym. I just want to know, is there something I can do that will help more? I don't know but i feel like its just not possible for me. They aren't fat, persay. just bulky. I would really appreciate your response. E-mail, phone call. whatever is convenient for you. thanks alot.