I can use 170s at 5'4. 172.5's would be pushing it. Did your fitter talk to you about that? Still, the fact that only your right ITB seems irritated is still consistent with a q factor issue. The right pedal is further offset than the left because of the chainrings. So, sometimes only the right ITB gets irritated.

But, honestly, I think the best thing is to revisit the fitter and talk about what's happening. A few tweaks might be in order.