Glow said I'd start my period on Sunday. Usually glow is always correct with my period or is only a day off. It's Friday and I still haven't started and do not have any symptoms of starting. I took a pregnancy test on Wednesday night and it said I wasn't pregnant. There is a big chance I am pregnant but when would it show on a pregnancy test or why haven't I started my period. Also does glow mess up big like this a lot or is it not normal. Because it's Friday and I was supposed to start this past Sunday.