Your entry port is Nha Trang and the exit port is HCMC Seaport. These are the two we have always used for your ports.  You can can also use Vũng Tàu Port for Phu My, both HCMC Seaport  & Vung Tau Seaport will work for the exit point.   Also set the start date for the Visa  you can use February 1 and it will be valid for entry anytime in the month.