I am currently breastfeeding my 6 month old son and have had only two periods

Patient: I am currently breastfeeding my 6 month old son and have had only two periods since having him era h 41-46 days long. My last (2nd) period began on June 10 and lasted 4 days. On June 16 the condom fell off during sex, so I took plan b the next day. Two days after taking it I started bleeding moderately for a few days. On the 22nd my husband assumed I was “on my period” and didn’t not wear a condom without me knowing. So now I am a little over 24 hrs post unprotected sex questioning if I should take another dose of plan b? That would be two doses within a week of each other, what risk does this pose to me and my breastfes baby? and what are my chances of even becoming pregnant with out taking a second dose? Needless to say we are set up next week for a vasectomy consult. Thanks for your help!

Doctor: