Questioning What I've Known

I've always considered myself straight, but over the past year or so, I've been thinking more and more that I might be bisexual. I've never been with a guy before but I've been thinking about what it would be like more and more. I had an opportunity a few months ago to hook up with a guy, but I couldn't bring myself to do it. I think I could still hook up with the guy, but honestly, I'm nervous.

So I guess my question is: should I give it a try? How do other people get over their fears or nervousness?