Temp plateau and new expected AF date

Hi ladies,

I’m wondering if anyone has any experience with a chart like mine below. My husband and I have been TTC for a couple months now and I’ve been measuring my bbt for about two months. This is my chart so far this month. This morning my temp was the same as yesterday. I’m 10 DPO with AF expected in 5 days (really hoping it doesn’t come!). When I recorded my bbt this morning it changed my expected AF date from 5 days to 12 days. My last AF was may 18.My cycles are pretty consistent (within a day or two each month) and there’s no way my AF would start in 12 more days. Any experience or advice on what this means and why that would happen? Is this a good sign or a bad sign??