I think that you will feel if you overdo it. I do sometimes and know right away so in time you will know how much is enough.
I also wanted to suggest replacing one cup with cup of home made milk kefir. You still get the protein but much more probiotic both in terms of number of strains and volume. Plus since you are fermenting it yourself, you are sure that it is fermented right (at least 24 hours) so that minimum sugar (lactose) is left in there.
I still eat plain Greek yoghurt but I also have about a cup of kefir daily.