Winger Jordan Chapell made history for the Gulls with the fastest goal the Devon club has ever scored, but it wasn't quite enough to beat battling Pompey at Plainmoor.
Former Sheffield United starlet Chapell hit the net after only 17 seconds with his fifth goal of the season.
But with the wind behind them in the second half, Portsmouth piled on the pressure and finally equalised through substitute Ryan Bird nine minutes from time.
"It just shows that if you keep plugging away and keep playing the football that we did today, you will get your reward," said Whittingham.
"We're disappointed that we haven't won the game, because of the way we played. Overall, we've got to be pleased with the performance, but not with the result."
Of Chapell's first-minute stunner, Whittingham said: "You always want your team to start well, but we didn't attack that first ball in as we should have done.
"But after that first minute, I thought we dealt reasonably well with Torquay."
Whittingham sent his team out early for the second half, but stressed: "All we said to the players was to keep playing the way they were in the first half and they would get chances.
"I can't ask for any more effort than they put in either. I thought we looked like the only team which was going to win it as the second half went on."
It was Torquay's veteran striker Karl Hawley who set up Chapell's 10-yard left-foot opener and the final outcome might have been different if McCallum hadn't missed a great chance, again laid on by Hawley, just before half-time.
But Pompey cranked up the pressure with the wind behind them in the second half and both Johnny Ertl and Jed Wallace went close before Wallace crossed from the right and Bird stretched out his right boot to wrong-foot Martin Rice and poke home the equaliser in the 81st minute.