This is above your pay grade.
Depression is a very, very physical ailment.
You don't hope and pray a broken leg gets better. Same thing with a broken psyche.
Talk to a parent or another trusted adult about how you've been feeling.
As for your female friend, she may or may not have been flirting with you. About the only way you will ever truly find out if she is, is to ask her.
"Sue, are you flirting with me?"
"Sue, since you're flirting with me, are you free Saturday night?"
Something like that^ and substitute her real name, of course.
You miss 100% of the things you never try to do.
But seriously, talk to an adult and at least see if you can talk out your feelings and feel better. 2020 and 2021 are hard years on everyone and you are far from alone when it comes to feeling down.