I've always had a thick head of hair and prefer having it grown out. Only problem is most of the men in my family I share genes with are completely bald. My Dad, his Dad, my Mum's Dad, her brother too, etc.
Even though I've always had a thick head of hair I've always had a prominent widow's peak and I do seem to shed a lot of hair so it's something I've always been kind of paranoid about but I'm told even if you aren't going to go completely bald your hair line will change naturally a bit as you mature during your 20's.
I am the sort of person who gets paranoid about lots of stuff and I've found, the best way to see if you're balding is to simply look at old pictures of yourself, usually on Facebook. Hope you figure it out, dude.