Look, I fell in love with my girlfriend on our first date. I didn't know it then, but I knew that something was different. You just have to be honest with yourself about it... is it REALLY different? Has this already happened to you with other girls? If so, then this isn't real love, and if you haven't had much in the way of relationships before, then it's probably just infatuation. The only way to really know if it's love is if you've been almost in love or had a HUGE crush or something, and some other relationship experience as well - so that you have something to compare it to. If it's the first time you've gone really crazy over a girl, I wouldn't worry too much about it, it's probably not love.