Plan B Safe while breastfeeding?!😕 Help!!!

Hi ladies,
I had unprotected sex yesterday with my husband. I was taking the pills since 3 months ago but I went on vacation and lost the package. Last night we had sex and I am debating if I should get the plan B pill. I am exclusively breastfeeding and have not get my period at all since I gave birth.
Do yuk guys think I can get pregnant even with no period and breastfeeding? 
Is it safe to take it in my case?
Please help!!!!!