Birth control question ?

I am 15 and was recently put on the pill because of my horrible cramps. It has helped some but I still have cramping during my period. My question is that I am going on a mission trip and my white pills (the pill that let's me have a period falls on that week. I am not sexually active so I have no risk of getting pregnant and was wondering if it would casue me any harm to take my white pills a week early or later so I don't have to deal with it overseas. I have looked everywhere online and cannon find an answer. Has anyone had this problem before? Have you taken your pills early or late? Did you feel funny? Is it safe? Any info will be helpful! I also don't want my hormones to be to wacked out either. I tried to call my doctor to ask but I have to make an appointment to even speak to her