You need to be careful when using fixture units to size for a TMV. Most of the correlations of FU to GPM are VERY oversized.
Generally, I use about a 40% reduction on the flow rate given by the curves. If you look at the ASPE Design Book 1 (if you have access to it), they give some various ways to size the hot water system in order to size the heater. This will give you the same information to size the TMV.