13DPO means 13 days past ovulation. They say implantation happens between 6-12 days past ovulation. Depending on when you ovulated, it may be too early. If you don't know when you ovulated, then you will probably need to wait until AF. If still no AF on 20th or 21st, then take another test. If still BFN, wait a couple of days and test again. If still BFN and no AF you may want to schedule a blood test with your doctor to go ahead and see if you are pregnant or if there is a reason why your period is delayed...
Good luck!
not to sound stupid but what does 13 dpo mean?
When did you O?
Most of the time you get BFP 13 DPO till 17 DPO
That's what I've heard.