@pythno Hi! Autistic (diagnosed within the last five years) here. I, too, thought it normal to be exhausted after peopling. I'm quite social, I'm good at talking with people, and all those other things. I even have quite high empathy.
Are you sure you don't stim? How about tapping fingers, playing with pens, chewing at the inside of your cheek, tense-relax specific muscles, wiggle your toes inside your shoes, hum, suck teeth, cluck with your tongue, snapping fingers, cracking fingers, rolling your shoulders ... all of those can be used as stimming, not just what the stereotypes say.