Douala is on a season-long loan deal from Sporting Lisbon.
The Cameroon international told A Bola: “I arrived here injured and I spent a month in recovery.
“I have been fit for close to three weeks but the truth is I only played one time.
“In case that this does not change, in January, I have to rethink my life and, therefore, the clubs that were interested in me before I came to Portsmouth.
“I think I have much more possibilities in France. Money is not everything in life.”