AF showed up

She showed her ugly head yesterday. I was hoping it was maybe implantation bleeding, but nope. It's way too heavy today. :( Is it possible for a woman's cycle length to change after a miscarriage? Mine was 26 days before I got pregnant in January but miscarried in Feb. Period came again at the end of March and my husband and I did the BD throughout my fertile window according to the app (which is how we got pregnant last time). I thought I was pregnant because I was late, but period came at 31 days instead of the usual 26. So I'm thinking my ovulation didn't happen when I thought and we missed fertile days.