Stop and think about humanity, and the length of time its been around. Humanity was primarily low carb for the vast majority of its existence. Certain subsets were zero carb well into the 20th century, and others remain low carb.

And yet, the species managed to continue to expand and expand.

I very much doubt that it's the low carb. Especially when you state that you are "moderately" low carb, not VLC. If it were the case that those who are low carb experience a loss of libido DUE TO the lack of carbs in the diet (a ridiculous thesis, on the face of it) then the lower the carbs, the lower the libido. And that doesn't happen.