How do I become more motivated?

I know this is long, but please read. I need help. Ive always been the stupid one in my family. The only two years I’ve made good grades were when I left private school and went to public school for my 7th and 8th grade years. And still, my parents were hard on me because my A’s and B’s weren’t good enough because it was public school and my twin sister was getting straight A+’s because the “curriculum was easier than what I grew up with”. Now I’m a freshman in highschool and I went back to private school, and everyone around me is extremely smart. I joined clubs, participated, got my A’s and B’s in the beginning, and then it all dropped. My friends are winning awards for the clubs when I did just as much as they did ( and I know I did ). All of my friends are on honor role. My math teacher went on maternity leave for 7 weeks and left us with a sub that dropped my A- to an F by mistake and didnt fix it until it was too late for me to sign up for honors next year. I didn’t get enough community service hours to be eligible for a new club next year ( missed by 8 hours ). My french teacher didnt let me into honors when I was one point off from getting in. My guidance counsleor is never in school so I cant talk to her to change things. Now all of my grades are dropping to B’s and C’s and F’s because I feel like the idiot of my grade that can’t get honor role and awards and I always do everything wrong. All of my teachers think im no good anymore because of it. My school makes us all think that if we aren’t perfect that colleges won’t even look at us. I’m scared.. i dont know what to think…