McCarthy believes his side had enough chances to have earned at least a point, but they were let down by their poor finishing.
"We had our chances, even at 2-0, and if we had scored it would have been a nervous end for them," said McCarthy, who had overseen three straight wins to take Ipswich out of the relegation zone.
"We have made progress as a team and had a really good run, so now we have to start again.
"We gave a bad goal away in the first half when we didn't defend a corner correctly and then we got done on the break, but it was a fabulous finish by their player.
"We missed our chances and that was the difference. We were on top in the second half, only to let them off the hook, so I am disappointed."