More urination than usual after sex.

Me and my partner had unprotected sex on 8th Aug ( last day of period was 3rd Aug). He ejaculated outside but maybe some pre-cum went inside the vagina. Rest of the time we had protected sex with condom on but he ejaculated within the condom while his penis was inside the vagina. I took Ipill the next day ( on 9th Aug, approx 30 hrs later). On 15th August ( 6 days after taking ipill) I had black clots of blood and later on 16th August, I had very light spots of red bleeding ( with small clots). The bleeding was enough to stain a panty but very less to even cover a single pad. The bleeding continued till 2 days and then till 21st I had brown discharge. Also, I am urinating a little more ( not frequent though). Now I am worried about pregnancy. 1. Is there any chance of pregnancy? 2. Was that a withdrawal bleeding or an implantation bleeding? 3. When should I take a pregnancy test for accurate results?