People say I'm good, yet i question myself.?

I'm a high school student, going into the tenth grade. I love acting, and is my passion. But lately , I've been questioning my talent. All my friends and classmates says I'm good and all. I even get a high mark, yet I often question my talent, asking myself "Maybe they are just mistaking effort for skills..." Could the reason behind me feeling this way because I'm horrible at singing? ( I THINK i'm tone deaf) Maybe it deal some sort of self-confidence damage on me? I mean, I keep thinking I'm not good enough or that I DIDN'T do my best. Sometimes after performing , I have this feeling of "ah, i should of went bigger" or "DAM , it would have been better that way.". Or sometime i felt like "SHOOT, i should have gave more emotion in my voice." etc. I didn't get the "drama" award for my grade , maybe this also gave me some damage self-Confidence? I'm not expecting answers, i just felt like i writing this out. I know being an actor , will always face disappointment, but still, its been floating around my head lately...