Nathanael,
I've looked into the matter briefly. If you are indeed a minor and the alleged harassment is taking place on social media, then the people who should be helping and protecting you in the first instance are your legal guardians. Furthermore, when it comes to the Internet, it is often difficult to take action when the people involved live in different countries, since the laws of your country may not necessarily apply to those of others.
Regarding the photograph, if it is not sexual in nature, it is also difficult to prove that it was obtained unlawfully, as it may have been previously shared by you or taken from a public source such as Instagram or Facebook. This is why people are always advised to be careful about what they post online.
On the other hand, you are also being accused of inappropriate behavior on the platform. From what I have seen, nobody is mocking any personal condition or characteristic of yours. If you are using something as serious as the harassment of a minor to justify or divert attention away from those accusations, then I believe you should reconsider that approach.