Chargers reinforcements might not be on the way after all ... Derwin James tells TMZ Sports he's not sure yet if he'll be able to return from a foot injury this season.
"I don't know, man," the stud safety says. "I just got to keep healing and we'll see what happens."
Derwin -- who's one of the game's brightest young defensive players -- has been out since the summer after he needed surgery to fix a foot he busted up back at Florida State.
The 23-year-old was put on injured reserve and was expected to make a return sometime this season .