How can I get reused to alcohol?

Used to go really hard on it when me and my friends got drunk. We never used to mix so we could get drunk faster and would usually throw up by the end of the night or next morning. After those nights my body no longer accepted the type of alcohol we drank that night so we would buy a new brand the next time. Always some new strat to get drunk faster like 60% or a alcohol taste that tastes really good like raspberry vodka. Now I am completely unable to drink alcohol without mixing it. I gag even at that sometimes. Anybody knows how I can convince my body it’s «not actually poison». Going into college and I really want to be able to drink everything again.