[Coffee.]

I'd say it'd be nearly impossible, definitely much under your 20% cut off for a morning after pill (which is what I assume you meant by birth control pill). If you two are at all interested in sexual activities, you may want to consider getting on a birth control method. You seem very anxious about pregnancy, and even if you don't plan on having vaginal sex for a while, being on a birth control method could at least give you peace of mind for any of these activities you're having. I was on the pill years before I had vaginal sex and it regulated my periods while making these heavy petting activities worry free.