Random slight constipation?

My period is starting in less than a week. I have a strong immune system, but lately I’ve been stressed and haven’t been sleeping well. My diet hasn’t changed in anyway... although I know I haven’t been eating as much fiber. I’ve been drinking so much water, my urine is clear.

It’s not so much that my body won’t go, it’s more I know I have to but I stop getting the urge to go a few moments in to sitting on the toilet.