Right, I had unprotected sex just over a month ago, I've had a two day period (usually lasts 5-6 days) wasn't really heavy at all. I've had 3 negatives so I assumed I wasn't. I still get bad cramping every now and then, and just a few days ago my boobs have been really sore and tender, seems to have got bigger over night. Feeling sick most days! I went to family planning and went on the pill, so I'm on the pill now, been on the pill 2 weeks? So will this have anything to do with it?

IT could. A lot of birthcontrol pills have those as a side effect. There are many reasons for wonky periods and some of it might have been stress at getting pregnant. When did you test yourself? In days after your period. You could still be pregnant, and the birthcontrol wouldn't affect your pregnancy, but it would be better if you weren't on them if you were pregnant. You might want to test yourself again to be sure.