Hi @zhen , welcome to the ReachOut forums, we are really glad to have you here. I am so sorry to hear about what you have been going through. Bullying can be incredibely isolating and emotionally draining to deal with. If you feel up to reading, we have these articles on coping with bullying here and here that might be useful for you.
Body-shaming is never okay. No one should be expected to look a certain way, and there's no such thing as 'perfect' or 'normal'. Though I understand that sometimes it isn't easy to think negatively about yourself.
Dealing with concerns around body image can be really tough to cope with. Have you got a trusted adult who you can speak to about this, like a family member or professional support person? The Butterfly Foundation offer some support and resources with this that could be helpful for you.
You mentioned that your teachers have ignored you when you ask for help. Have you had the chance to speak to any of your teacher about what has been happening? Are your parents aware of the bullying?