Miss

Patient: I had a baby 10wks today , my first period came back on the 5 th may, I had sex withdrawal method on the 17th May and ovulated on the 19th may,, though I had a second period in the month on the 21st may,, there is no chance I could get pregnant because I had a second period a few days after ? If so how could that be? And how do I test as I had two period in the month

Doctor: