Not reacting to alcohol the same anymore

Apologies if this isn’t the right place to post but I just wanted some advice. I am a 29F and this might just be age but why is it that I can’t drink alcohol like that anymore? One decently sized drink leaves me with a crippling headache in the morning. But when I was 25ish I could go out and have drinks without an issue. I remember my limit was 3 drinks and 3 shots any given night max and I would be fine in the morning. Given I drink maybe once or twice a month now compared to my at least weekly from before. I workout consistently, live a rather healthy lifestyle, 10k steps a day etc. I just don’t see how all of a sudden one drink is throwing me off.