Your bodyfat is dropping but it isn't significantly low, e.g. <12%. The dropping of it may be the upset in your cycle. I'd wait to see if it happens again next month --- I really don't know if its a readjustment period that needs to occur or its just the significant change in bodyfat that is occurring all of a sudden.
either or.....there is no set rule to 12%...Ive seen a 10% woamn never miss a beat and Ive seen a 14% one lose it completely.....I think that it will continue to dwindle as the bodyfat goes