Welcome carolyn0226....availability is poor this year on some routes and I can see that SFO is one of those routes.
You should have used the "Book and Upgrade" tool when booking your flight. Using it would have prevented you booking a class of ticket that wouldn't have qualified for upgrading with miles...although the ticket price would have been a lot more. Anyway, upgrading from WT to WT+ is a waste of miles and money.
No idea of Virgin so can't help you there.