E.D at 18 or just worried?

I'm 18 and have had Erection difficulty's. Almost a year ago I was with a girl at a party and decided to go to a room. I fingered her and when she tried to give me a hand job my penis stayed the size it is when flacid. I tried to get it to go up myself but it wouldnt. I do think the reason why this happened was because i had drank alot of alcohol and it was around 5am and I was half asleep! Since then it happened again with another girl. I didnt feel aroused when i was in bed with her. This could be down to the fact that she wasnt doing anything to pleasure me. My first girlfriend was who I first started trying things with. This was when i was 15/16 and I could easily get it up. I feel like since i first tried having sex and not succeeding I have thought that idea over and over and my main worry since then has been whether or not its going to happen again. Its also frustrating as all my friends are sexually active and i feel like im the odd one out.