Most Helpful Girl
If she was single, maybe go with what your gut says.
However, since she has a boyfriend already, waiting might not be a great idea. Ask yourself this, do you just like how she looks and comes off as, or do you talk to her and truly know her personally? If you just like her appearance and the idea of her, then I think you should weigh if waiting is good idea (in addition to the fact she might never leave her boyfriend).
I know how intensely and almost irrational a crush can feel at your age, but try to see it from all perspectives. Don’t feel like you have to chase other girls if you legitimately don’t want to, it can feel a worse forcing how you feel anyway. My best advice in this case is just to respect her relationship, and try not to get to too invested in possibilities and expectations.
Most Helpful Guy
It's dumb dude. Get a girl that doesn't have a boyfriend.