I no longer live in the US. The coffee there has stuff added. Where I live in Costa Rica, the coffee is pure and a friend here told me I would have no problem. I was skeptical, but I discovered I can drink one half cup and no problem with about one half of it milk. Cannot do the same with coffee from the US..
When in the US, I used to drink a cup of decaf from Dunkin Donuts which did affect me.
I do not know where else, but when visiting a few years ago, I saw coffee from Costa Rica in Whole Foods.
If you find, I suggest a half a cup and test for a few days. I do eat a bit of dark chocolate, but always with protein, usually a few walnuts or other nuts to balance out any effect from caffeine or sugar.