try googling 'effects of fasting on hormones'. i haven't but you might find something explaining it there. the hormones are affected by changes in insulin levels and vice versa.
but i'd be concerned it may not be the uterine endometrial lining shedding since you haven't had a cycle for 12 mths and the last one hemorrhaged even! when you fasted, not good.
under these circumstances i would suggest you get a blood test to ascertain whether your platelets, iron, rbc etc. are capable of handling a fast.