Greetings!
As you may have read, the airlock is NOT a good indicator for fermentation activity. If the carboy warmed up, got shaken, etc. then bubbles could happen due to pressure difference.
Use a hydrometer. That is really the answer, and the answer to many beginning questions. If the FG is steady across a couple days then it is done fermenting.
At 2 1/2 weeks a standard beer should be done fermenting, but is still always good to check. If it is still indeed fermenting and you bottle too early, then you risk over-carbing the beer (and in extreme cases, exploding bottles).