Implantation bleeding ?

First off I do not have a uti and I'm not dehydrated. I have this pressure pain that I feel like I need to pee constantly anyway I did my normal cp check and there was very very light brown on my finger so is that implantation bleeding or no? My cp is high and firm but I can't tell if it's open or closed ? I think I'm 6dpo today but a calculator to test for pregnancy said I'm 8dpo. I ovulated on cycle day 24. I'm so confused. I do have a appt Friday but I just would like some insight on what's going on