Missed period, cramping for two days but negative pregnancy test. Is something bad happening?

Laura 🇬🇧

I’m usually really regular and due on my period today. I’ve been having cramping for two days and a tiny bit of spotting but no period has come today and I took a test but think it’s neg

I guess this would be 13 dpo if my cycle is behaving although I didn’t do OPKs this month so I guess ovu could have been later.

I’m concerned that there could be something wrong as pre menstrual cramping for two days with no show of period isn’t normal.

I’m seeing my GP tomorrow as been trying for a bit with no joy and just turned 38.

Does anyone have any advice, experience of weird cramping but no period?