Are your parents willing to help you find a different therapist? This one sounds clueless. Your GI problems, if the tests are negative, would seem to relate to your anxiety and stressors from bullying, etc. It's hard when you're underage and don't have much control over who you get help from, but if your parents can come around to changing therapists or if you have an adult ally (teacher, school counselor, neighbor) who can talk to them and maybe recommend another, that might be one way to go.

Don't give up, though. If not now, when you're a legal adult, find a good therapist and create a good life for yourself.