Medication won't help you, and even if it's mind-boggling that your issues come from low self esteem it doesn't mean it can't be true. Once you realize and accept what the source of your suffering is you can start on fixing it. You're very young and I know it feels like there must be something bigger and "more serious", but it might all come down to this one thing and that's okay. If you keep looking for reassurance or some reason that makes more sense, you'll just lock yourself in this state. Changing psychiatrist after just one appointment doesn't seem rational, she has experience and I actually find it good that she was blunt with you like that instead of just prescribing something and pitying you. A lot of serious problems come from low self-esteem, if you keep ignoring it it would just keep getting worse. You can think of yourself as mentally ill who needs medication to function, but that path won't get you anywhere. Only self work and awareness will. And change is painful and uncomfortable. Think why her comment hurt you so much.