I think "lesbian" means different things to different people. To me, it means that I want to be in a relationship with a woman instead of a man and that I'm primarily attracted to women, but it doesn't mean I'm not at all attracted to boys.
Identity, choosing to label yourself a lesbian, is something that is totally self-defined. So, if you want to be a lesbian who also likes boys, that's alright. If you want to be a lesbian-identified bisexual, that's cool. If you want to say you're straight up bi, but you have more experience with girls, that's rockin' as well.
Just for your own experience, you might want to think about why the idea of being sexual with a guy scares you. Is it something like the feeling of stubble, or more like the possible power imbalance? The pregnancy risk? Just not knowing what it's like and if it's different?
Knowing what about "boys" in general or a "boy" in specific scares you will probably help you figure out how you want to identify yourself. And, identifying what about "boys" scares you might help you clarify what you want in a sexual partner, no matter their gender.
That'd be my suggestion. Good luck!
[btw- I put boys in quotes because I'm kind of sensitive to my own sexism lately... Not all boys are stereotypical "boys".. Gah! Essentialism vs. Social Construction! Gah!]