Am I gay or Bi or something?

I am 19 in college and I like to think of myself as straight but sometimes when I watch porn I look at the dick and want to have sex with them. Sometimes when I have sex with girls I think of guys. I kinda want a guy to ************ so bad but I don't want any one to know. Also me and my best friend who is straight we kinda hit on eachother as a joke. we run around in speedos and stuff but I kinda want to have sex with him for reals. There is times I feel like I want to play with cock alot more then vagina. what do I do?