This is something that can happen and is something that isn't unheard of during fasts like in ramadan."My period is usually regular and was supposed to come 4 days ago. I'm currently fasting so my eating & sleeping schedule are messed up."
As described in this thread: M.I.A or, Dude, Where's My Period?, missed periods can have for a variety of reasons... but taking a look at some accademic studies you're right that fasting affects things too.
Here are the results of one study where 20% of respondents had their periods affected during ramadan:
https://www.ncbi.nlm.nih.gov/pmc/articl ... /table/T2/