Very interesting question. It certainly sounds like this bike should be fitting you better after all the effort your LBS put in. Plus the OCR is a relatively upright bike compared to the giant TCR and I think compared to trek wsd too. If you've been riding and your in relatively decent shape you should not expect pain to be a part of the adjustment. Have a buddy watch you ride and see if you are hunching or something.
I'm especially interested in what happens as I am considering going from my trek wsd 2100 to a giant TCR. I never loved my trek. I want something to LOVE.
Oh, one more thing, I am on a 52 cm and would go to a s giant not an xs. I'm 5-4, how about you?