I don’t know what’s going on

My period comes at the end of every month into the other month like clockwork. The last time I had my period was the 28th of February. It was supposed to come on the 30th of march and we’re 9 days into April and it still hasn’t come. I took a pregnancy test yesterday and it shows negative. I’ve always had cramps a week or two before and then during me period, I’m still have cramps everyday but no period. I don’t know what’s going on and I’m frustrated. Anyone else experienced this before?