I miss my periods sometimes

Odna • Healer , Intuitive Oracle Card Reader, Empath, Lightworker, Herb lover , Crystals lover, & Essential Oils lover . DIY chick
Hi, I miss my periods sometimes and I hear it is attributed to high stress levels ,  how true is that ?
Also when I do see my period the subsequent month , it's sometimes an abnormal red color close to black with a hint of red .
Pls answers
Thank you