Well, I would suggest testing again in a day or two if

doesnt show.
Some women dont turn a hpt + for quite some time.
Any time your cycle is way different than normal it is good to pay attention to it.
Implantation bleeding doesnt always occur at the moment of implantation (6-12dpo), the blood can pool behind the forming placenta and leak out at any time.
Also, u might want to check with your dr if

doesnt show to rule out ectopic pregnancy.
Keep us posted!