Hi, If the pills you missed were meant to be consumed in the first half of the cycle, it is possible that contraception may have failed. The spotting could either be a breakthrough bleed secondary to disturbed hormonal milieu or an early period. To clarify, you need to perform a serum beta-hCG titre estimation as this is the earliest and best way of diagnosis at this juncture. Thus pregnancy can be confirmed/excluded. Blood test can be done as early as a week or ten days after suspected ovulation. You may also need a trans-vaginal sonogram and physical evaluation by a specialist. Hope this helps.