What are some specific signs to tell I'm gay?

Well the obvious ones are that you are attracted to women and that you are not attracted to men. Having a passing curiosity about girls would not necessarily mean your gay.
I knew a gay guy who fell in love with a girl got married and now has three kids. No woman other than his wife has ever interested him even slightly.

In all honesty I doubt there is a girl out there who didn't at one point either think about kissing a girl or actually do it. It is like this big unspoken thing between females. If that's all it is then you probably aren't gay, trust me that's normal. If you are at all attracted to the opposite sex then you are not gay. My advice is if the opportunity arises to kiss a girl then go for it a kiss will tell you so many things. You will know from that kiss alone whether you are just curious or actually gay.

You fantasize about the same sex, and you have no interest in the opposite sex. You get excited around a girl but not a guy.