What makes you think you can trust the cottage cheese maker about contents though? I'm sure if they tested cottage cheese you would see 5-10% variation. Some of that will just be testing methodology and some will be natural variation in the product. People get overly hung up on the numbers, between measuring and variability there is probably a +/- of 10% on any figure you recorded for the day in my fitness pal or whatever tracker you use.
+/-10% sure, but there were much larger discrepancies in the test, plus others found some amounts of heavy metals, so I'm not talking solely about the protein content, but what else they put in there.
I'd trust a dairy product from a regulated market more than this unregulated market.