Ahoy barret munkey ---
I live with back pain (on and off) and when it flares up, IWB and shoulder holster carry are very difficult.
On those days I ankle carry (which I used to hate just the thought of) but once I tried it, it works just fine, you'll need to wear pants that are slighty baggy to conceal well. Of course the manual of arms is different: drop to one knee, pull up pant leg, etc. Never thought I'd get used to it, but now I always ankle carry, when my back is good, there is usually a Sig P238 or a PPK or a J-frame down there as BUG.
On bad back days, its usually a Sig P239 or SA 3" micro 1911 on the ankle, both of which are heavy guns. (Heavier than the Glock 19)
Galco make an excellent ankle holster for the Glock 19.
At 21, you do not want to mess up your back, you got plenty of good years to go before Father Time catches up.
PS --- When I hang out with my liberal (anti-gun) friends, they have no clue, ankle holsters make for great deep cover.