Drogba left Stamford Bridge for Shanghai Shenhua after scoring the winning penalty in the Blues' UEFA Champions League triumph over Bayern Munich in May.
And the 34-year-old Ivory Coast international claims he had wanted to stay but could not reach an agreement due to Chelsea's intention to move in a new direction.
"My priority was to stay at Chelsea to finish my career there, at the highest level, but the club wanted to bring new blood into the group," he told France Football.
"So we had negotiations for months without finding any agreement.
"I had the offer from Shanghai but I hesitated and hesitated. Finally I followed the advice of my former Le Mans coach and wrote two columns with the pros and cons of moving to China.
"I made my decision to leave before the Champions League final, even if I didn't sign anything at that moment.
"If we hadn't won I don't know how I would have reacted. Victory helped me to leave. It was the right time to go."
But the veteran striker could be set for a return to Chelsea - to train with the team during the Chinese off-season in order to prepare for the Africa Cup of Nations with Ivory Coast in January.
Drogba added: "At first I have to ask for authorisation from my club and then from Chelsea. And if everyone agrees it is possible I could go and train there ahead of the next Africa Cup of Nations."