Bisexual or Lesbian?

So, I was having a conversation with a coworker the other day and she asked me if I considered myself bisexual or lesbian. And I really don't know the answer to that question.

We were just talking about relationships and I was having a small issue with my girlfriend that was upsetting me. We were talking about how I've slept with guys in the past, even though the true love feelings for them was never there. My gf on the other hand, dated a few guys in high school, but has never slept with a guy. My gf said that she didn't usually date bi girls so it was a thing that we overcame early in our relationship. Honestly, at this point, I'm not interested in anyone other than her. I don't look at other people, I don't see myself ever being with a guy again. But I don't see myself being with any other girl either. I don't ever really pay attention to labels or sexual identity, but I was kinda taken back by the idea that I didn't even have an answer for this question.

I think guys can be attractive, but I don't want to have relationships with them nor do I have any emotional attraction with them. But I don't really feel any attraction to other girls either. I guess I'm just so invested in our relationship that it doesn't even matter to me, but it kinda made me really think "what do I identify myself as?" And I still don't have a good answer for that. I guess I would say lesbian because I am only attracted to and in love with my girlfriend.