3 neg pregnancy test, still pregnant?

On 30th March, there was penis rubbing on my vagina which lasted for hardly 10 seconds. There was no penetration or ejaculation, but I was anxious about pre-ejaculation, so I took a postpone 72 within 48 hours, on 31st March. My periods were due on 8th April. On 7th April, I started bleeding lightly which continued till 11th April (morning). I took two urine pregnancy tests, one on 13th and other on 22nd April, both of them were negative. My next period would have been due on 7-8 May. I started bleeding on 6th evening, which continued till 10th morning. My periods are usually of 4 days, as well but I wasn't sure if both the bleeding were my periods or what? I took another urine pregnancy test today, on 20th May, which was also negative. What are my chances of pregnancy? Please elaborate.