Bell shot 24 goals, including the last in a match that wasn't settled until the final seconds.
The Firebirds appeared doomed when trailing their heavily-favoured hosts by six goals at three quarter-time.
But the Queenslanders produced a gallant rally to score six of the initial seven goals of the last term and reduce the margin to one with 10 minutes remaining.
After a frantic period, the Thunderbirds still led by just a goal with 50 seconds remaining - but they had the ball, which ended with Bell and her match-sealing goal with only two seconds left.
"It certainly wasn't easy," said Woodlands-Thompson, who conceded the challenge of keeping her title-winning squad together next season.
"We are, I think, one of the only teams to do multi-year contracts and a lot of those are up," she said.
"And after a premiership, the offers come thick and fast so I'm sure all of our key players will get offers possibly financially better than what we can do.
"It's very hard to build a culture and it's something special when a team can stay together - I don't want to lose anyone."
Queensland failed in their bid to become the first club to win the championship from fourth spot but captain Laura Geitz was proud of their tenacious display.
"It could have truly gone either way. I don't think we have to beat ourselves up too much about being runners-up," she said.
Geitz was outstanding against Adelaide's star shooter Carla Borrego, who finished with 26 goals from 33 attempts. At the other end, Borrego's fellow Jamaican Romelda Aiken threatened to single-handedly win the title for the Firebirds with 39 goals from 47 shots.
Thunderbirds 50
Firebirds 48
- AAP
