Weird situation, cant find posts that match

Ok so we started ttc 5 months ago when i had my arm implant removed. This month I had a positive opk on cd 28 and assuned that i ovulated on cd 29 and then at 6 dpo or cd 34 i started having brown spotting. This spotting was very weird, i had to wear a liner but its a little more than just a drop or two. It has been pinky, brown, and really dark brown. I absolutely wouldn't call it a period, but it was 9 days of this brown stuff, and then the day i was supposed to get my period the spotting stopped and im now 3 days late for my period. All hcg tests have been negative and it doesnt fit the descriptions of implantation bleeding, as its a little (slightly) more than just wiping and seeing it. I wonder what could be going on? Did i just have the lightest period in existence? Is it still possible that i could be pregnant even though at 16 dpo it is negative?