Being near bald at 19 isn't that uncommon for guys as far as I am aware.
I first started losing hair at about 16, but it wasn't that noticeable,really. When I joined the army reserves (Territorial Army) at 17 it was a bit more noticeable when I had my hair buzzed off. I was given a #1 and blended/faded #0 back and sides by the troop barber. My first ever really short haircut. My next haircut after that was a shaved high & tight (recon) which I kept more or less until I was about 21. After I left the army reserves I grew my hair back out again and got my first proper head shave when I was about 26.
By the way, welcome to this great forum.