When does Sculptra actually stop building the new collagen?

I am young and had 2vials of Sculptra at the age of 27 and 28. My last vial was 21 months ago. I want to know when the collagen will stop growing. Some Drs say it stops at 6 or 10 months and definitely should have stopped at 20. However I have photographs and ultrasound scans that shows my skin thickness is still growing - the 1st scans from 15months ago and the second from 20 months ago. I am so upset and my face is huge. When will it stop growing? Is there anything I can do to stop the process?