Sprintec

I'm on sprintec to balance my hormones because of pain and I don't miss a lot but with it being summer and me always doing something it's very easy to forget. Im just wondering are you supposed to just forget about the one you missed, or take it when you remember? Because I've heard that doubling them on one day can hurt you but everyone has told me that's what they've done. I'm getting married next year and my biggest goal in life is kids so if I was told I couldn't have kids I would go crazy... I've always had a fear that I can't have kids.