Great post, but to clarify - 200 US doctors prescribing 35/mo would equate to revenue of $330M (assuming diagnostic sale at ~$3300 USD). The $150M is based upon 9 doctors/clinic across 12 clinics, representing 108 doctors.
That being said, there are 480+ fertility clinics in the US, and if all of which prescribed at that rate (with assumed avg. of 5 docs/clinic), we would be seeing the $3B.
Something I'm missing?