Can anyone explain my strange response to alcohol?

My (college-aged male) response to alcohol is very strange for people my age. There are some nights where I can pound 8-9 drinks and be totally fine, and some nights where just a single beer makes me throw up. It feels like every time I go out drinking I have to be hyper conscious of my pacing at first or else I get nauseous, but once I get 4-5 drinks in it ceases to matter and I can drink as fast as I want with no issues. Chugging drinks is a general no-go for me as well as I get nauseous. I’ve been tracking my food/caffeine intake to see if it’s something I’m eating, but the only conclusion I’ve drawn from that is I feel the best if I wait 2-3 hours after eating before I start drinking. This has been going on for a while now- the first time I ever drank in a social setting, I had one beer, and then someone observed that I was very pale and my pupils were very dilated, and then I went and threw up. I just want to be able to enjoy drinking in social settings without having to be hyper conscious of my pacing all the time or worrying about throwing up. Does anyone else have a similar issues, or can anyone explain what might be happening that causes this? (This community is for curiosity, not karma farming.)