Ovulation or implantation bleeding?

I am experiencing some light brownish pinkish discharge. It started last night but I have no cramping or anything I have just been feeling a little bloated the last week or so. I have a very irregular period so I am not sure if this is ovulation bleeding or implantation bleeding but I have always had consistent periods when I get them (lasting about 5 days and always starts heavy with cramps) and haven't ever had ovulation bleeding. Has anyone had any experience with either? My husband and I just stopped using any birth control but since I am irregular I am kind of expecting it to take awhile for us to conceive.