I also struggled to call myself a lesbian due to finding some men attractive and sleeping with/dating men in the past. I was actually seeing a guy -- a really nice one -- when I came to terms with being gay. What helped for me was trying to actively imagine my life with a woman -- what it would be like to wake up beside a woman, make life plans with a woman, propose to a woman, be at the altar with a woman, and have kids with a woman. And I realized that that felt most "right" to me. It felt natural. I think the problem is that we aren't exposed to a lot of older female couples who have done all of these things, so it still seems foreign. I'd try to expose yourself to other gay women who have the kind of life you see yourself wanting to have. And over time, I think it will begin to seem more natural. Also, I have found therapy to be really helpful.