Just go with the flow and don't try too hard.
What you could do is do things with people of different genders.
For instance, go out to a party and hang out with the different crowds.
From my experience, I've gone to parties where most of the lesbians would team up when playing drinking games and socialize all night long together. There would also be straight women who just like to hang out together and talk about men all night long. Then there are straight men who like to do macho things, but also like to hit on women. Finally, there are gay men who can be very flamboyant and hit on each other while drinking.
So, pick one group and see how it feels with that group. If you're wondering about whether you are a lesbian, then you can hang out with the lesbian crowd. They will of course start hitting on you. If you enjoy the feeling or have an urge to start hitting on them, then that might be what you are. If you're feeling uncomfortable with what they're doing, then you might have a different preference.
Then you could go with the straight women and see how it feels to just be with women. If you find yourself talking about guys like they are, then you might be straight. That would lead to hitting on the straight guys. If the guys start hitting on you and you actually feel good about it, then you could be straight.
What about the gay guys? I dunno, I just added that to even out the equation.
Sometimes, personal feelings can't always be dealt with alone and being with others can help to realize our true feelings.