The Spain international penned a two-year loan at San Siro last August after a disappointing three-and-a-half-year stay at Chelsea.
However, Torres struggled to make an impression, managing just one goal in 10 appearances for Filippo Inzaghi's men.
A move was subsequently engineered in January, with Milan completing the permanent signing of Torres before allowing him to return to boyhood club Atletico Madrid on loan in return for Alessio Cerci.
Torres insists he harbours no ill-feeling towards Milan, but realised that that he had to leave Italy.
"I went with an expectation and with an idea which, later, was not met," he told AS.
"I went to Italy to play, to be an important player, and at no point did I feel like it. I was in and out of the team, I played on one day, yes, and on another, no. This is not what I had spoken of from the beginning.
"My dealings with the club were excellent and I don't have anything to reproach. But when you see it’s not going to get better, nor change the situation you have, you are uncomfortable."
Torres has scored three times since returning to Atleti, his goals coming against Real Madrid and Barcelona in the Copa del Rey.
He will aim to break his Liga duck for the season against Carlo Ancelotti's men in Saturday's Madrid derby at the Vicente Calderon.
And Torres is fully focused on coming away with three points.
"You notice that the people are looking forward to the match," he added. "Not just the squad but the fans.
"It's because we can compete. We are going out to win. We are not going out to see what happens, as it might have been before.
"We know very clearly what we have to do."
