Any suggestions on irregular periods and keeping up with everything?

Jennifer • 30, no kids ttc for 3+years, self employed baker, ovarian cancer survivor and own helping the homeless organization.
Its so hard to know when your missed af, since myself and I'm pretty sure a whole lot of other people too. So any suggestions because I drive myself nuts knowing I have irregular af but always think I'm pregnant towards the end when I think I "missed" a af. ?