God, I'm such a noob, but I'm gonna give this one a shot. I've got something similar going on. I can't tell you what to do, but I can tell you what not to do, so that should help a little.

First, don't make her choose. This will scare her and it'll end before it even started. You need to take it to the next level if you haven't already. If you guys have a plutonic relationship now, start getting closer to her physically on these spontaneous outings. If things seem to be going alright, kiss her, nothing big, but definitely on the lips. If you don't know where you stand, run your fingers through her hair first. If she seems cool with that, it's a good sign.

Damn, I'm suggesting what to do now.

Oh well, I think it's good advice, nonetheless.

Good luck buddy.
Mr. E

Charity is gay.