The number of people on the upgrade list has nothing to do with the number of available seats on the aircraft, it only indicates how many people have requested an upgrade and are hoping to ride up front. You can have 30 people on the upgrade list, only 12 F seats in the aircraft, and of those, only two seats actually open and available for upgrade.
If you got one, be glad. You won.
I was very lucky on a flight home this summer when I somehow leapfrogged something like 30 people on the upgrade list. Given that our flight out was among the last before a nearby thunderstorm arrived, I was very happy indeed.