Fasting and Periods

I hope this post is appropriate for this group. If not, I'm sorry.

I've had irregular cycles which I believe stems from use of BC through out my teenage years (regret it now). As a result, my hormones are out of wack. My Obgyn wants me to get back on BC to "regulate" them and I just don't want to go back into it. I have noticed every time I fast for three days (water only fast) on or after the third day my period comes. I did a 21 day (water only fast) and after three days AF came lasted for a week (Nov.5 - Nov 12). I continued my fast as usual then on Nov. 22-26 I started spotting (when I wiped) and I was scared something was wrong with my body. For reference my fast ended night of Nov. 24. Now it's December 31st and I have not had my period and hpt comes back negative. I'm just wondering if my AF came Nov.22-26 but I don't believe it did because I'm normally really heavy and those days was just blood with CM when I wiped. Only one of those nights I wore a liner to bed and it was soaked. Then normal (wiping) the rest of the time.

This was the first time I did a 21 day fast. I normally do three days. Also, is it unholy to fast during your period? I feel like the church always emphasized that women were unholy during that time of the month and shouldn't pray or fast. However, that was from the Old Testament. Jesus came to reconcile God and His children's relationship so that unholy once a month no longer stands right?