Due date?

Brittany
A standard <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">due date calculator</a> tells me that my due date is 3/15/16 but another calculator I used had me put in my average cycle length, which is 25 days not the normal 28, so it gave me a due date of 3/12/16. Which one would you go by? I have one app saying I'm 4 weeks 4 days, another saying I'm 4 weeks 5 days and another saying I'm 5 weeks. Lol. So confusing!