Question about my BBT chart

Last month, i began charting my bbt. This time last month it was going all over the place, but now its pretty constant at 98.6. Someone suggested earlier today that my thermometer might be dying and that is why my chart this time is so constant. I checked my bbt this afternoon and it had risen to 99.4 so I know it works fine.

My pre-ovulation temps were about 97.3-97.6.

Im 9 DPO, CD 23 if that helps. Does it look promising at all?

Top is this cycles chart.

Bottom is laat cycles chart for comparison.