I've been fitted, but of course I added a front hydration and had to move aero bars and cups around which I think totally messed with my cockpit placement. (of course they were tiny but still).
Does spending more money on an aero helmet make sense like ed said? Then I think about Brian Stover saying some aero helmets make some people slower and people need the right one for them. I'll just buy an aero helmet that I get on sale with no clue if its helping. Thats why i just went with the aero road helmet for versatility and maybe some aero gain.
There are several ways to figure out CDA from a race file, each with different levels of sophistication and accuracy. Some people use Best Bike split. I have heard people use winsock which I never tried. I have some tools that are not commercially available that I use. Robert's chart is a good estimator.
Better is to learn to aero test rather than rely on post race analysis.
Moving your stuff around probably didn't change your aero profile much. I suspect your fitter went for comfort over aero (unless he tested you)
I think what DD often says is "if you aren't going to test, select the one helmet that is top 3, 99% of the time". For example, a GIRO aerohead falls in that category. I think you will be hard pressed to find a person that an Aerohead tests slower than a road aero helmet. A buddy recently tested a Giro road helmet vs Aerohead and he was willing to give up a few watts for heat. He tested both one day for aero watts, then another day for heat and went for heat over aero.
Here is a chart Notio used to show how good to bad could impact speed on given watts