B777 Captain reported a communication breakdown occurred between the Captain and ground personnel regarding Final Dangerous Goods (DG) documents. During taxi; Ramp requested the aircraft return to the gate due to a weight and balance problem.

Narrative

As Captain; I questioned the crew prior to our pushback request" to confirm that there was no "planned Dangerous Goods (DG);" to which both FOs replied "no;" as just prior to this I had sifted through the printed paperwork on the pedestal to find this document; if it existed. I could not find one. Then; after the pushback began; and maybe even before the parking brake was set - as best that I can recall - a "Final DG" form came out of the printer automatically. I knew that somewhere something went wrong since we need to acknowledge with a miscellaneous ACARS "DG acknowledgement code" before pushback when we have DG. Instead; and surprised that we hadn't seen the "Planned DG" form; we sent the "DG acknowledgement code" message after the pushback was complete. As a crew we wondered if the loading team was at fault or if there was a communications error. Then; after engine start; we were notified by Ramp that we needed to return to the gate because of a weight and balance problem. And so this added event made us believe that the problem was not anything the pilots could have prevented."