Earliest you can have unprotected sex while on B.C. (birth control)?

[So_Needless_2_Say]

I stopped using B.C. for about a month and a half (july to mid aug) for health reasons. And i just got back on them this past friday. My bf comes back from deployment for a short visit this coming Thursday.. Is it safe to have unprotected sex (being that by the time he gets back i've been continuously on B.C. for 13days straight)? Or would i be putting myself at risk for getting pregnant?

Oh BTW (by the way), i use the pack entails 3wks of active pills & 1wk of nonactive pills.