Here is what Larry came back with from Three Shepherds in Vermont about your issue. I forgot to tell him that you had very tiny curds so I sent him your first post on this thread today. Here is what he said so far:
Thanks for the link to the forum. It is true that some cheesemakers are very reliant on acidity measurement (TA and/or pH). As we mentioned, it definitely can be an aid for gaining insight on the biochemistry of the process, and for some cheeses (e.g., mozzarella), it can help a lot with knowing exactly when a critical step needs to occur (stretching at pH 5.3).
Both Linda and I have had many years of lab experience, and understand the value of getting precise measurements. However, we learned cheesemaking from Europeans who take a sensory approach to cheesemaking. Using your eyes, olfactory sense, taste, and feel can also give tremendous insight into the process as well. We are not trying to say that one way is right and will make better cheese--but it is interesting to note that on our 1997 trip to Europe, only one out of 28 cheesemakers measured acidity with lab devices. And we have consulted with many, many farms who have had major issues with expensive pH meters, so the strips end up being a better investment.
As far as the ricotta, whenever we make mozzarella I always make ricotta from the whey, and it works extremely reliably. However, we have never made mozzarella using citric acid. I do know that when we have tried making ricotta from whey that is very acidic (below pH 4.7) it can be very tricky to make ricotta from it. So perhaps the citric acid is playing a roll. It would be helpful to know what your friend is observing and what procedure he is using. Just let us know.
When is your wife coming to Vermont? It would be great to see her (and you) again.
Keep us updated on your progress.
Larry and Linda