Scared shitless after a night drinking

I’m 18, drank about half a mug of I don’t know what (tasted quite strong), slept about 20min later, didn’t feel particularly drunk at all, except getting a little tired, maybe I wasn’t awake long enough to see the full effects of the alcohol. So question is, since I’m pretty young, is my brain fucked now? I mean, have I done some lasting damage to my brain? I only drank once before, when I was 17 (and I got a little tipsy)