Turning 21, noticed a bald spot

[marzipanlies]

Hey all! I'll be turning 21 in a few months. Recently noticed a sort of thinning/balding(?) spot around the vertex of my head. I've always had kind of thin hair but I definitely have never noticed this.

I looked back at some candid pictures from about a year ago, and I definitely think this is new. No one has ever mentioned it (though I'm not sure why they would). I'm just really surprised given how fast this seems to have come on. The more I look at it the more I think it's pretty noticeable. I wear my hair long and this is just going to ruin everything about my look.

In terms of family stuff my dad has a big old male pattern bald spot but a fine hairline. My mom's brother has a full head of hair and my maternal grandfather has thin old person hair but doesn't seem MPB-ish.

I'm also hugely stressed and don't sleep enough and don't eat right and drink/smoke too much. So, basically I'm an average college student. Could it be environmental stuff? I've sort of read that most people on these forums discount that but thought I'd ask.

Anyway here's some pictures
Overhead - http://i.imgur.com/PbijPX7.jpg
Bent forward - http://i.imgur.com/Qq3c0Tv.jpg
Normal hair - http://i.imgur.com/L03UV9Z.jpg
Hairline - http://i.imgur.com/E8QQhsU.jpg, http://i.imgur.com/pWZSVxi.jpg, http://i.imgur.com/90UgZ1a.jpg

I think my hairline is fine but I'm not the best judge. The one side looks weird because I had kind of a Skrillex undercut thing going on and I'm trying to let it grow back out, hence the unevenness.

Anyway, let me know what you all think! Thanks!!!