Advice?

💕Francésca💕 • Mommy and wife 💚💚 8 year old boy and my baby boy on the way! 9/12/08💙 12/7/16💙
AF was due on the 18th. I took a test that day. Had a BFN. As of today. I have sore breast. (Really sore) and mild constipation. What's the best test?