Adjusting Period Problem

Ashleigh • Gave birth to my first on 2/21/15. Lincoln James. 💙
I need to adjust my period but it won't let me change the end date when it falls on a Sunday. I started my period early and need to move it up to today and ending on Thursday as opposed to starting on Thursday and ending on Sunday. If I change it to start today it has it ending on Sunday which would be too long of a period for me.