I was once going through a very hard time, and felt very rejected. It was terrible, and Boruch Hashem I had a very good friend who shared my pain. She bought me a lovely card, and wrote me this beautiful note how Hashem loves us and how we can’t depend on anyone except our Father in heaven.
It is very unfortunate that teens and adults get rejected by frum teachers and schools and friends, and then it affects our frumkiet. I hope that for “teenager”, time will heal and Hashem will give you the strength to battle all your inner wars. You have your whole life ahead of you, G-d created you for a reason, you are special and don’t let others control your emotions. You are reaching out for help, you said you were getting therapy, and you seem to be on the right path. Just keep on trying, may Hashem guide you to the right supportive people, and you will be stronger as the result of your struggles.