Have you ever heard about making a coffee concentrate by soaking coffee in cold water for 16 hours, and then when you want to have a cup you just add hot water. Coffee made this way is much lower in acids, and tastes good too.
I've been drinking decaf lately and using coconut milk and stevia. This may sound really crazy, but sometimes I find it to actually be medicinal. If you don't like coconut milk in your coffee, then organic whole cream has the least amount of carbs, and I think would be a better choice than soy milk.