Yes your cycle can change. Also the dates that the days of the week land on are diff each year, so it may be the same but the b/c of that it seems diff.

I want to thank. I was scard that it was me. Thank you so much

Mine changes really easily. It tends to change along with my diet, activity, and stress levels. Be sure to write everything down and keep track of it though. You can know a lot by tracking about your body.