I have had nothing but 100% bisexual feelings my entire life, but I've never had sex with a man. When I was your age, I had the same worries that you have now. I didn't want anyone to know that I was bi. I was actually your age when I started dating my ex-wife and I was with her for almost 20 years. We have kids and they are my world, but I only did the marriage thing because that's what I was "supposed" to do. If I had a chances to go back in time and do things over again, the second time around would be much different. Instead of jacking off while fantasizing about sex with guys like I did in high school, I start having actual sex with guys in high school. I would never marry my ex again if given a second chance. I would only marry a woman that was supportive and involved with my bisexuality. I would become involved with the bi community so I could be around people that understood me.
Basically, I think you should act on your sexual desires and enjoy yourself before you start having the same regrets I have.

As far as a relationship with a guy, ny views have changed. I used to think it would make me gay. I know better now. If I meet the right person, I dont care if they are a man or a woman.