ANYONE ELSE RELATE??

So my period is very late. pregnancy tests were showing up negative. I had a blood and urine test done at the doctors, negative. I’ve had many symptoms similar to the ones you’d have when pregnant. Mild stomach cramping, lower back pain, frequent urination. And the doctors can’t seem to find what’s the cause of my period being so late and these symptoms. No I’m not “more stressed than usual and that’s making my period late”. My periods came every month since I’ve been off birth control (almost a year) and my stress has been the same and has never seemed to effect my period. I just want to know what this could possibly be. Has anyone else experience this before?? 😩