Outside of the US, upgrades to F are something exceptional. European/Asian/MEA airlines do not try to fill every F seat and keep F very exclusive.
Unless you get the email to upgrade to F, or possibly do it on the QR PC website using QR avios or credit, you would not get upgraded.

The F catering loaded for 2 pax is much more extensive than for one pax. With many J pax, they could possibly accept one more J pax with upgrade from Y to J given the large number of J pax. That is not possible when doubling the F catering.
Some remarks in your post might even suggest that they need to load the catering from DOH on the incoming aircraft. If so, it would be impossible to get an upgrade at MLE airport.