What can I do, if anything?

I’m 16 years old and my love life has been really really wack, the last girl I’ve ever had feelings for broke my heart when I made a big mistake with her about 7 months ago. I havent really liked anybody since then, not seriously at least. A few weeks ago I met this really cute freshman girl at my school, and over the past few weeks I’ve begun to start to develop some feelings for her. It generally takes me a long time to grow to like someone, and I’ve had a lot of near misses in the past 6-7 months. Anyways, this girl says hi to me everyday between periods in the halls when we pass each other and at dismissal, and she’s really flirty and just pokes me and stuff like that. My problem has been that I’m uncharacteristically shy around her, it’s usually really easy for me to flirt but for some strange reason I dont talk much around her, which hasn’t ever happened to me before. Also, she got her phone taken away about two months ago and isn’t sure when she’ll get it back, so before I can even text her I’ll still have to get her number, and she’s hardly ever online.
About two days ago, I found out from my best friend, who’s a freshman as well, that this girl doesn’t see me like that. I don’t blame her since we haven’t talked a whole lot, but she flirts with me a lot every time we see each other. Turns out she likes one of my friends, or so I’m told. I’m just asking for any advice about what I should do in this situation, I don’t really want to give up on her and have to start from scratch again. Ideas?