Frustrating

So glow keeps shifting my timing around.  It moved my fertile period back, now says my O date was 10/23 and pushed my period date out.  I'm assuming it's because of the temps I've been recording. (This is my first month using the app and first time temping). But it's driving me crazy cause I told it I have a 28 day cycle, which is pretty much clockwork. I entered my period info back as far as it would let me. Ugh. ::end rant::