Is it normal... to watch lesbian porn if you are a striaght girl.???

Yes. You're attracted to it because girls know what we want and find pleasurable. As to regular cock to vag porn (lol :p) it's more for the pleasure for guys.

Well I have a bf of 3 years... I only watch it if I'm alone and can't get pleasured by my bf and if I'm in the mood too... But besides that I won't watch it...

Well if it makes you feel any better I am a guy and have looked at gay porn occasionally. It is sort of whenever I am in the mood for something different. I am 95% straight the other 5% is well I don't even know or care. I would just examine my self if I were you and see if looking at it correlates to you liking other girls. I wouldn't get stressed you probably are just curious as many people are but are to shamed to admit it.