Fertile window changed overnight!

Sonel • Mom of 2 boys aged 4 and 6 and expecting a miracle 3rd baby naturally after doctor said it was impossible. 4 failed iui’s and a corneal ectopic that severed my left tube
Hi ladies. Yesterday my fertile window was supposed to start today and when I logged this morning, I saw it moved forward and started Monday which means it is almost over. I am so confused. Why would it change so drastically? I checked my average cycle in settings and it is correct at 29 days. Glo now predicts my cycle to be 25 days. What is going on? Please help!