6 -7 days after ovulatıon ı have ımplantatıon beleedıng (ı thınk-ıt was 4 days lenght) and my perıod ıs 3 days late. But all hpt results are negatıve.ı had backache durıng ımplantatıon bleedıng or whatever ıt ıs.do you thınk ı am pregnant?

Implantation bleeding is somewhat rare and if it does happen, it would be very light and last only a day... no more. A backache due to implantation is not very likely, so that could have been due to something else.

If you're sure of when you ovulated, then spotting could be due to a low progesterone level or B vitamin deficiency. Really, the only way to know for sure is to speak with your doctor. If your period doesn't come in a few days, test again then call your doc.