The closed-cell foam pad should have offset the cold conduction of the air mattress. I think you were losing your heat from the top -- the cheap bag.

Changing to dry clothes is more important than you would think. Even if you changed everything except your socks, you would probably still be cold.

You might also consider wearing a wool watchcap under the bag hood. Or a baclava that covers your head and neck.

How was the meteor shower? I planned to watch and got sidetracked.

Sue