ED and only 16 what could it be?

welp here's the deal i'm 16 about to turn 17 and when ever i got to masturbate it is still a little soft nothing like it used to be not only that it takes like what seems forever to get it up. i don't even wake up in the morning with a stiffy anymore in fact i havent even had that in like a year. the thing with it being soft only started like 2-3 mounths ago. oh and here recently i haven't even had a high sex drive so much so my girlfrend has even noticed it for instince one time i didn't even feel like making out.....wtf! what could this be this is so annoying i completly refuse to go to the doctors. here lately my and my GF have been talking about having sex but i'm scared that if we do then of course it won't be very hard. would be really sad if i had to steal some viagra at my age. no i'm not depressed used to be...