Well, for me, a proof of being in love is when I can actually screw up enough courage to tell the person that I like them. It´s a measure of the feeling that I can´t keep it locked up inside, and that despite my shyness and trouble expressing my emotions, I overcome it and just say "I like you." Even if it´s not conventional for a girl to say it first. Crushes.....you kinda think "I like you" but don´t actually have enough emotion within you to actually go for it and
do something, you know? With love, it grows and grows and eventually you just have to say something. At least, that´s what love is to me.
I´ve only been in love once, and the guy broke my heart after a few months, so I can´t really say I´m experienced in love (or anything
near that, really). But I definitely believe that it was really wonderful and something that made me mature in some ways. I found myself talking more than I usually did, smiling at him, enjoying his company so much.... it was a nice time, then, like discovering a part of me that I hadn´t known existed before.
I hope that someday I will fall in love again and that person will love me back and we will live happily ever after (barring the usual fights within normal couples, lol, I´m not THAT clueless).