Fasting affecting period

So I am a good weight for my body (120 5'3) and I will fast for around 24 hours a couple times a week because I'm still trying to loose about 10 pounds. I have lost around 3-4 pounds recently. My period was supposed to begin on the 21st and I am exactly a full week late. I know I am not pregnant, never had sex, but I wanted some of y'all's opinions on if this fasting I am doing is why my period is not showing up. I was also woken up yesterday morning to excruciating abdominal cramps, I have no clue if that is related. I would love some advice