For some reason when I drink alcohol I can get drunk after literally a beer or two, however from that point i dont seem to get drunker.

I’m 20, 6.4 and genuinely have no idea how this works. Ive drunk obscene amounts of alcohol in uni (a whole 2L bottle of vodka + other drinks throughout the night) and stayed the same level as when I have only 1 or 2. This is verified by my friends who confirm that I am still coherent and about the same from the first drink onwards. I have never passed out or thrown up other than accidentally mixing alcohol with ADHD meds one time. What’s the scientific explanation for this?