Am I pregnant?

I've had my period but it was dark,it was actually brown. I haven't gave much though to it but I have been having lower cramps(stomach) migraines,pelvic pain and I'm just wondering. Me and my boyfriend have had unprotected sex but we did the withdrawal method. It's not that we are trying but it's like what happens,happens. If it's meant to be it will be. I'm just wondering that is there any way you can be pregnant and still have a period? I've watched 'I didn't know I was pregnant' and people have had there period. I'm just off the pill about a month ago or a little more. Thanks!!