Ay sis, 13 days late with negative PT is confusing talaga, especially with symptoms like sore breasts and cramping! A few of us moms have been in situations like this, and honestly ang best thing is to see your doctor na para sure, they can do a blood test (hCG) which is mas sensitive than PT, or check kung may other reason bakit delayed ka (stress, hormonal changes, etc. happen din). Don't stress too much in the meantime, but don't wait pa, kailangan mo ng clarity!