What should I do when my "crushes" are my only source of happiness? Am I in love with the feeling or the person?

That's up to you to figure out. Make a list! What do you like about them? And then make another list: what do you like that is not them? Sunsets? A certain song? Running headfirst into wind? Open fields? Star-gazing? Driving at night? If your happiness relies on the warm fuzzies of thinking about certain people you don't even know very well, maybe it's time to look at who you are independently of them. What you like, what you want to try doing, what you dream of experiencing. Happiness is one of those things that are better when shared, and can come from many different sources. You just need to find them!