I had roughly 2.5 shots and nothing, yet the other day 1 drink had me drunk

I took 2 and a half shots of straight vodka and nothing. The other day I drank 3 drinks, 3 shots, and a little more and I was fucked. After 1 Black fly I was very buzzed and on the brink of drunk. The first sip I took was almost 2 hours ago, and nothing. This is the third time alcohol has ever touched my lips in my life, yet nothing. I don’t wanna drink anymore tonight because I want to save the rest for another night, but fuck why is my tolerance like this?