Why sometimes I simply can’t get drunk?

Honestly no idea what sub I could ask this, so here it goes:

I’ve heard that if you drink alcohol constantly you get resistence to it but that’s not me. I rarely drink, and of course I’ve gotten drunk sometimes.

But this weekend it’s been about a month I didn’t use any kind of alcohol, and I actually drank A LOT. Didn’t got drunk, only regreted cuz my stomach ended up hurting during the hole party and I even thought of inducing puke to make it stop.

It has happened a few times before and I have no idea why? Another few times I drank way less than I did yesterday and got drunk easily.