How can I be more confident ?

I’m a 18F I’ve been struggling with my confidence almost my whole
Life. It all started when I was in elementary when kids would bully me over my hair & body, mainly my body since I was / am overweight. Plus my brothers would pick on me also. My mom did the best that she could but hearing all those mean words made me so insecure ; Growing up with the-constant bullying from school to my house I started to isolate. I wasn’t able to really focus on school all think about my weight and nothing else I didn’t have any friends I would I come to school everyday insecure and wanting to die all people talked about was my weight. I was only known for being big and weak for not fighting back at people telling me I’m worthless just because of my weight I hate it so much I
don’t want to be fat. I have been trying to lose weight but then I’ll just stop be use I wasn’t seeing any progress then the negative thoughts
Of what others said to me i ended up saying it to myself I gave up on the thought of losing weight and just was eating more and more watching tv hoping it would just end. Me now I don’t have those negative thoughts anymore. I do love myself but I hate seeing all the saggy arms,stomach,thighs. - last summer I did lose over 60 pounds I’m happy over that of course but that only happened because I was depressed. I ended up gaining the weight back and I’m just in a daze i am working out here and there but my bad eating habits came back I keep on going for losing 10 pounds to gaining like 20. It’s not just my body I’m not confidence in , the way it’s also the way I talk & my iq. I’m doing bad with school since I was having bad smoking habits trying to forget about my past just for that to become a problem I am taking a break but I’m not understanding anything in class , I am reading & rereading watching YouTube videos but even then I’m not really understanding it I understand it takes time but I need my mind right now so I don’t be the dumb fat junky little girl. I believe I can do better and change not
For others but for me to finally put my mind to rest to let my little self there’s more to life and she is beautiful, deserves love & peace not just with her body but with her thought I want her to be able to achieve what she thought she could never do.

Sorry if this is was too long or if I’m over telling the story 😅
I’m practicing on writing more and opening up my feelings.