true love?

You can tell if you are in love with a person if you keep on thinking about him. You can say that you are deeply in love with a person if you can already sacrifice anything for his own sake. But these information about love is just what I heard from other people. I don't think I have already felt in love with someone and I don't want to be like the others who would say that they are already in love with a person even though they know that it is just a crush. One instance that I remembered is that when a friend of mine fell in love for his first boy friend. She fought for it and even argued to his father for him and hopefully he understood his situation but unluckily they broke up after almost one year.