Missed pills

I missed my last 4 pills in March (19-21) and i started my period on the 23rd of March. I had unprotected sex on March 29 (husband said he pulled out) and began my new pill pack that night. I did take Plan B Monday the 30th. I was supposed to have a hysterectomy due to having adenomyosis, but with hospitals doing only emergency surgeries, they’ve rescheduled it. What are the chances that I could be pregnant? We have a 14 and 18 year old, and another child is not something we desire to have. Thank you!