With us, the urologist first met with us to discuss the medical history & our history of TTC. He did go over possibilities of what the zero count was from - it could be a physical blockage, missing the "vessel" (can't remember exact name) that would carry the sperm from testicles for ejaculation, genetics (as in our case), or other reasons. Our RE had already run some bloodwork, but the urologist of course ordered some more. He then did a physical exam of DH's equipment including the testicles, which was funny to see the look on DH's face when he told him to drop his pants.
So, we left with the lab slip and made a followup appt for a couple of weeks later. Luckily for us, our insurance at that time covered all of this so money wasn't a factor and we immediately got the bloodwork done. I can't remember if your insurance covered this or not, hopefully it does.
Good luck, Aimee!!! I hope you get some answers soon!!