I'm seriously fed up with this whole situation, and need answers pretty desperately!

So there's a girl who calls me "bro" pretty often but i don't know the exact context she uses it in, (just friendly, brotherly, or just instinctual slang) because i knew her before this year but i was never friends with her until this September, but i like her and can see us in a relationship.

At the beginning of the school year she got my number off a girl and used to text me pretty frequently (1 to 2 times a week) and start most of our conversations. From there i texted back a bit and we both started kind of flirting with each other. I wouldn't see or talk to her a lot in person because i only had one class and she didn't show any CLEAR signs of interest, but there were some small little signs with her but we would text a lot more.

I've tried hanging out with her but each time i asked she would have a legitimate excuse why she couldn't make it. Now it's December, and she hardly texts or talks to me anymore and i feel like it's too late to make a move.

Here are my options: Ask her friend that i'm also friends with if she's interested in me, text her that I'm interested in her, just leave it be, or take whatever your advice may be.

btw, leave a link and i'll answer yours if you took the time to answer mine.