Help please

My period came on april 20 and ended the 24th I had sex on april 26 he came in me I took the plan b on april 27th because I felt confused about having a second child a week after I got my period on may 2 and ended may 4. I tought about it and decided to have a kid so than we had sex unprotected on may 14 and he came in me . My question is do I go by the period of may 2nd or April 20th and what are the chances of pregnancy?