time troubles are common in shorter time controls for obvious reasons. However, there is one HUGE factor that could help. If you go into your "settings" you can turn on "premoves." This allows you to choose your next move during your opponent's turn and as soon as the opponent moves, then the computer will automatically make your desired move for you in 0.1 seconds!
If you need help enabling premoves, then checks the forums or chess.com articles on it as there are lots of deeper information there. Just be careful about using premoves too often since it essentially locks in your move (although you can cancel the premove if you do it before the opponent moves [by right-clicking on most PCs]). Premoving is a great asset due to its speed, but it is best for forced moves and recaptures or you might find yourself hanging pieces because of an opponent's unexpected move 
In my last Blitz game, I had 0.8 seconds on my clock, and checkmate in one by force.
While I was waiting for my opponent to move, I highlighted the piece I needed to move, and just kept rapidly tapping the checkmate square as fast as I could. When he moved, it said my time ran out, and didn't credit me with the move. I don't think is possible because I was tapping maybe three or four times per second.
Has anyone else had a similar experience?
Is there a better way to get that final move in, besides what I tried?
Yes, I know, just move faster. lol