Hi, I Was Put On The Cerelle Desogestrel Pill When

Hi, I was put on the cerelle desogestrel pill when my son was born, I've been on it for 6 months.. Forgotten to take them sometimes and I sometimes take them at irregular times. My periods have been normal, except now. I am 3 weeks late and have really bad tummy pain, headaches, back ache and I constantly feel bloated but I am still eating more than I usually do?