I have 3 <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period apps</a>. One says my period should of started on the 28th, another says I'm supposed to start tomorrow, but this apps <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period tracker</a> says i should of started my period today. So when can I take a pregnancy test!? I'm so confused.