I was in the same boat as you. I was unsure if i was bisexual or not. I now know I am.
If you see a girl and you think she's attractive doesn't necessarily mean you're bi.
If you start thinking thinks like "she has a nice body/butt/breasts ect" and it's not jealousy but you actually feel a little sexually attracted to that girl.
Imagine yourself with a girl and touching her and she touching you and kissing and if you are turned on or intrigued by the thought you might be bi.
At first I considered myself to be bi curious because I didn't really have anything to truly make myself know i was bi or not.
I found out i was bi when I actually kissed another girl.
I hope this helps. Feel free to funmail me.
I am straight but i know some people who are bi-sexual.
I guess if you start to think of girls in a sorta "nasty" way, then you feel sorta attracted to them, as well as for guys. If there is this one girl you have these strange feelings for, as to want to be with her all the time 24/7, then chances are you are developing some type of feeling.
Just follow your heart, and remember there is nothing abnormal of liking guys and girls.
knowing that you are bisexual is not that hard, just try to find someone you can kiss (girl) and if you like it and you think its hot then possibly, and if you dont like it then there you go, just take it from someone who IS bisexual.
it's kinda self explanitory, if yur physically attracted to girls AND boys..yep