Do you think I have a gift for music?

At 13, you've got a LOT of time to find out. Certainly, you've got a great start--you play by ear, I ume you can read music, you play or are very familiar with several instruments, you can compose (just need to develop that into a career), you understand musical parts (melody, harmony, orchestral sections), and you "feel it" (VERY important for performing and composing). Sounds like talent to me. The question is, where will you take it (and I don't mean the other way around--it's often an act of will, not a happy accident.)