your young, skinny (by skinny i mean very little muscle on your frame)and probably not very strong.
without going into a ton of crap here:
start "west side for skinny bastards" immediately.
keep your "cardio" but do it in the form of actual running exercises(they fit perfectly into the template above)--because these can build muscle too.
start eating. a lot more of everything.
if you are eating 1800kcal/day and you are getting 50% of kcal from protein, thats about 225gms of protein a day. thats GREAT! now just eat a bunch more carbs/fat and you will be doing fine.
check out the thread "bulking for college impossible" for some good ideas on some easy shakes and other good info.
dont waste money on supplements. eat food. read more.
if your fat loss goal is simply a goal to lose some fat because youve been slacking--i wouldnt sweat it. gain mass. by the time you gain 20lbs of muscle you will probably find yourself leaning up along the way.
i know where you are coming from . at age 24 (when i started training seriously) i was 6'1" 165lbs (10%bodyfat). pretty damn skinny! in about 2years i was weighing 210(at a lower bodyfat). i busted my ass, learned everything i could(still learning) and ate and trained like a war horse.
at age 19 you have everything going for you right now. start kicking some ass..stick with it and you will make AMAZING gains.