No, watching lesbian porn does not make you a lesbian. Sexuality is complex. It is very possible for a woman to be turned on by fantasies of other women, including porn, and be more turned on by men in real life.
Also I'm sorry you went through that bullying in school. It makes sense to me that you would be confused and wondering.
Exploring our sexuality is healthy and so is learning about ourselves.
It is ok to be attracted to just men, or just women, or both, btw. I wonder if you feel like being a lesbian is wrong bc of what your peers put you through?
But yeah, in my opinion, sexuality can be complex. I've heard people can be turned on by fantasies of situations that they definitely would not want to experience in real life.
And, I think you're right about the bisexual individual who bullied you. She was probably projecting her insecurities onto you.