Welcome to FlyerTalk.

Hindsight is a great thing isn't it?

For future reference, you can find out from Expert Flyer or from the Emirates website whether upgrades are available before you book, as well as calling.

All is not lost though, as upgrades may become available again before you fly. Keep an eye out for them or set up an alert with Expert Flyer (paid service). Upgrades are often released just 24 or 48 hours before a flight. As a Silver member you can also request a miles upgrade at check in or even on-board.