I think the bravery comes in working on the issue in the first place, then making the most of what comes of it.
I think the more you think about where you want things to go, and examine your feelings and behavior in the situations you are in, the small opportunities open up for you. Like you smiling back at the girl when she threw the paper ball at you even though you were stunned by it. Did you
feel brave in that moment? (I am really asking, maybe you did. Or maybe you reacted, not thinking "I have to be brave now"). It "just happened."
In that moment, if you hadn't set a goal for yourself of trying to make friends and connect with these girls, if you hadn't thought about how you react in situations with people who might be potential friends, you may not have reacted the same way. You furthered your goal of making friends by smiling, a choice in that moment based on what you've been working on inside yourself.
You may indeed make one big brave push to say or do something sometimes, but I think great things are accomplished in small steps most of the time.
I wish I could just have friends already.
I understand, personally I find it difficult to be patient with it all. I do find that if I'm "patient with the process" (as my therapist says) it turns out better than I could have imagined.