Well many people grow to the point you've come to. I myself reached it several years ago (i'm 25 now). From the age of 16 to about 19-20 whenever I'd drink (not that often, but as often as most of my friends) moderation was something I didn't adhere to. I would get thoroughly trashed. Rarely would I vomit that night, but as sure as the sun rising I'd spend a portion of the next day (sometimes the entire day) recovering. I never did anything dumb while drunk or embarassed myself (beyond vomitting of course and the like), but the hangovers just became too much.
In recent years I drink with much greater frequency but I've not been "drunk" in a good long time. Legally yes, but incoherent hell no. My hangovers are worse in recent years which has put a serious stop to alcohol ingestion, but additionally I just don't really enjoy the feeling of a room spinning anymore like I used to. I've become a social drinker as opposed to a social boozer
Give or take I can now reasonably estimate at what point another beer is going to trigger real pain the next day and then it's just time to stop.