I've never heard of nitro in coffee. It's definitely something I would try, so I am glad I read your post before stumbling into it on my own. I don't drink a great deal of caffeine either, so it's likely I'd respond similarly.
Do they sell it here in the States anywhere?
It's superloaded and beyond anything I can explain. It's a wild ride and I honestly could never be convinced to chance it again after that BUT since you don't drink a lot, maybe go with half a serving of what they give you first. The nitro makes it much more powerful... I really don't know why it's needed but it's an adrenaline junkie kind of drink ;)
It's available all over the world now, I got it in Hong Kong but I know for certain they have it in the states, maybe just Google and I am sure you'll find exactly the same brand I had this experience with!
Tread lightly, this was not an experience I would wish upon anyone <3