It definately sounds like you're quite young. Are you sure you
want to be in a relationship at your age?(Which i'm guessing
14-15).
In another post i have stated that i have almost lost 2 close
female friends because i told them i like them. I misinterpreted
their signs, even though i was really close to them.
Now ask yourself this, are you sure she likes you?
If yes, then good for you, ask
her out to be your gf.
If no, you're not certain, then
bring her out for a few more dates and then prepare roses, surprise
her together with the question.
Another matter is your friend. If your friend likes her too, yea it
can get a bit messy, but if he's really a good friend, or one worth
keeping, he will not ignore you because of this, (unless of course,
he really likes her more than you.)
Its all a matter of choice. But the most important thing is to
ascertain her feelings. Don't misinterpret!
Good luck man4nth.