I can't be with "xyz"

I have always had lots of crushes on people I can't be with because it's either illegal (no family stuff dw) but like professors, directors, people who work with my parents and people who I could be with but I feel too young and think they would be weird about it? I am 17 and fancy guys who are like a good 10 years older than me... Weird? Usually people who are smart and funny, not overly sexy but I always seem to fantasise about this one teacher, my drama teacher. If he wasn't married with a little baby boy I would actually go for it and be real flirty. Same with an actor I once worked with, he was so sexy oh my gosh but I thought he just saw me as a little kid. Advice? Always seem to fancy the wrong guys AND it makes me feel bad because I fancy them more than my boyfriend. Don't get me wrong I like the guy i am dating but if they every stood next to each other I know who I would chose... It's getting ridiculous now!