help: young love part 2

Ok so last time I told you the situation and it's only been like a week but oh my god I need advice..

I swear she was barely like this until afew years ago, she was the innocent one in the group to me until we had a christmas dance in school. She started flirting with me, and I know it was a friend way but I swear at the time it made my knees buckle. Now it doesn't make me do that cause ive gotten more used to it and she's became more subtle but today we were face timing and I realised she wants me to flirt back??

Like she keeps setting me up so I can compliment her and giving me opportunities to make moves but it's not that easy cause she's straight and to her this is all harmless. Seriusly its eating me alive I want to tell her but we're young and she's so oblivious that I know it would make us drift apart.

How can I be more comfortable flirting back and still not tell her? Any tips?