Ovulation

I ovulation week was from the 1st to the 7th of February according to my chart. But I only had sex on the 5th as that was the only night I’d seen my partner that week and on the Friday which was suppose to be my peak ovulation I started bleeding pretty bright red which isn’t common for me for about two days but stopped now just brown spotting. Is there I chance I could of conceived on the 5th? If so that would make me 6 DPO today, I’m having quite a lot of cramping, dull but definitely there in both sides of my lower tummy, I have taken a test already but just a cheap strip and not sure if I’m testing to early and that’s why it showed negative... is there a chance I could be pregnant?