The visitors halted a run of four straight Premier League defeats with a goalless draw at the KC Stadium, but it could have been much better had Dorrans put away his 10th-minute penalty after Victor Anichebe was hauled down by Jake Livermore.
Instead, Allan McGregor saved his fellow Scot's poor spot-kick and neither side created any real chances of note after that.
Irvine was pleased to have stopped a losing run, but left cursing that vital moment.
"It is does stop the run of the results and that's good, that's a real positive without a doubt," Irvine told the BBC.
"But we could have won the game. Obviously, the penalty is a key moment.
"Goals change games and had we scored then who knows what might have been.
"We didn't have enough of a threat in front of goal and like I say the penalty, had we scored it, might have changed things."
That being said, Irvine was impressed by the manner in which his struggling squad reacted to that set-back.
He believes it could have proved the catalyst for the hosts to go on and seize the initiative, but his side did not allow that to happen.
"We started the game very well. I was worried we might not be able to deal with the penalty miss mentally because it gave Hull a boost, it gave the crowd a boost as well, but we coped with that and I was really pleased about it," he added.
"It was certainly a tense game, and why wouldn't it be with the current positions of both sides?
"It's a tough place to play, it’s tough when people are scrapping and trying to just get something to give them a boost.
"The effort of the players and the way they went about things, I couldn’t fault at all. I don't think anybody could ever question the effort they put in."
