How do i drink without feeling so sick

Im 20 and started drinking very occasionally at parties when i was like 17. When i first turned 17 i was able to drink whatever without feeling it in my stomach and drink shots like nothing.

This year now I just can’t and the sight of seeing someone take a shot makes me gag. Like I need to drink alcohol with a lot of mixers to just be able to take it in. For example i forced myself a few times on different occasions to do a shot and almost instantly it just feels like my body rejects it, its like if i drink too much alcohol or if the drink is too strong in a short amount of time my body will just reject it and set it right up.

Im asking this because I wanna return to normal and take shots like i used to actually be able to and get properly drunk because I miss the feeling of getting smashed a few years ago.