Help?

Hi, my period has been late for about 17 days now. I have irregular periods as well. I am also sexually active I think the last time was around august 30th. He pulled out way before (ik not the safest) but regardless Its been really dry for me these last few days and i was wondering if anyone could have a clue what it is. I took three seperate test. Literally from september 8th to today. All came out negative. I just want advice as to what is wrong with me and if anyone experienced this before I'm planning on getting birth control on Tuesday and im getting the implant and im wondering if that'll also affect anything.