BBT chart confusion - issues with progesterone

Firstly my son was still born back in July so it could still be my cycle getting back on track but I wondered if anyone else had similar?

Initially my temperatures went right up, but they have slowly got lower, and today (5dpo) have hit the cover line - has anyone else ever had anything like this and still got pregnant?

I’m worried I have issues with production of progesterone - I have been cramping a bit the last couple of days and my breasts have been really sore which I would normally put down to progesterone during the TWW but surely this wouldn’t be the case if my temperatures are this low?

I had peak LH strips from cd19-cd20 and then a low fertility faint one in the evening of cd20 so I assumed I ovulated in cd21 which all my apps have confirmed since from temperatures but now I feel confused and unsure about it.

I have an alarm set every morning so I take my temp at exactly the same time every day.