Hey I had a similar surgery 12 months ago (they came in from the front and took out c5, fused c4-c6 with screws.) Are you thorough with your physical therapy? I never did physical therapy and really regret it. Don't have a bike fit but I kind of doubt a fitter would be of much use, you have a unique medical case. What works for me is riding less aggressive, more upright, sounds like you found the same works for you. Listen to your body.