Hi i came off the depo injection in october last year and been trying for a baby but since yesterday i been bleeding dark brown blood wot does it mean?

Probably nothing: The kind of bleeding that you're having is very representative of a gradual shedding of the endometrial lining--sometimes characterized as a prolonged "withdrawal" bleeding. A great way to maximize your chances in a situation like this (e.g. irregular withdrawal bleeding) is to utilize an OTC (over the counter) ovulation kit to determine when you're most fertile. Good luck!