Hey ladies, I'm 39 and after a MC in May and no luck getting pregnant after 4 months I decided to start BBT charting. What I discovered was Glow was off, sometimes way off and I had missed my Ovulation window. I was using OPK strips but those were so open to opinion (dark enough, not dark enough) ugh! I started in September but  I was not consistent. October, I became strict. I took my temp at the exact same time EVERY day, checked my cervical position and CM. I used fertility friend which puts a more accurate cover line on your temps and allows you to add symptoms, cm type and cervix position in conjunction with your temps. Plus, there's no stressing and testing hcg too early. You wait for your temps to show you if it's AF or BFP on the way. Here's my pregnancy chart- you can even see the implantation dip and then temp spike after.