Am I lesbian?

I am married to a handsome man and I love him a lot we been together for 5 years. I don't have any complaints about him, but I don't know what is WRONG with me, everytime we have intimacy, I have to think about women in a sexual way, that is the only way I cam have am orgasm. I have tried to watch straight porno but it doesn't turn me on. But when I watch lesbians porn I feel incredible. Please leave respectful comments. I am worry.