HELP!

Mae • 20.
I have a blood condition  called von wilbrands, apart of this condition is that I don't have the proteins in my blood to help it clot properly this has made my periods very heavy and I get really bad cramps, my period has never gone light on me. But this month it was, it came over a week and a half late which doesn't happen and was only spotting and a small window of very light bleeding, I usually bleed through a tampon every hour and I didn't bleed through a single one in a whole day, you could still see white. I still feel maybe pregnant but don't want to test cause well there was blood. But I've read you can bleed a little. Why would it be so light? No changes in medicine I'm with the same person... advice?