I don't believe in myself

I'm a 17 year old kid and I am a quarterback. As of today I am reinventing my throwing mechanics and learning a whole new way of throwing and I have summer practice starting Thursday. I am so discouraged and I am putting in the work but Im scared of shitting the bed because Im reworking my mechanics. I have been playing quarterback since I was 6 and trained my ass off with trainers since i was 8. I always play on all the good teams and all star teams except Im always the backup. The only time I started was 6 & 7th grade years where I got my head kicked in and then I got my head kicked in my freshman year and then my sophomore at a lower tier school I shat on all the JV kids and then did average on varsity with my coach telling me how much of a piece of shit i was for no reason (This coach lives off his dad paying his rent and his 6 banger camaro his dad bought him and he plays madden all day). I have no confidence in myself and I feel like I suck at everything except football. And i'm not even that good at that it feels like especially having to overcome everything I was ever taught right now and I work a shit load harder then the guys who are recruited but they're better then me. I had to transfer out of 3 (transferred to a premier high tier program after first semester of sophomore year but I got no reps so i left for my fourth school) I have no faith in myself. Please help me. My dad calls me a fucking pussy and a crybaby because I always complain about how i suck instead of looking on the bright side. Also, I hate myself because I feel like I'm not good at anything else and I don't relate to anybody my age. I have no friends and everyone says how mature and old I act. I work on the way I look and I'm not saying i'm doing everything I possibly can but I'm pretty ugly for how hard I work. I'm like a 6.5-7. I have abs but I have a very wide frame and they aren't the 8 pack skinny boy abs but I can't bulk up and get a super wide manly frame because I'm a quarterback. And I have big ass legs with no thigh gap. Only things redeemable are my hair, my eyes, and my white teeth but I have a dorky ass smile so that doesn't even matter. The girl I lost my virginity to was an 8 but she was a psycho alcoholic so that doesn't mean much and my first kiss was a 8 but she was nuts too. I only have one full fuck body and 3 giving/receiving head bodies. So as you can see I have nothing except football and I don't even believe in myself.