Well, in all honesty, I would suspect just a wonky period
rather than pregnancy at this point. Conceiving naturally
past 40 goes down each year that goes by.
I would see if a period starts in the next two weeks or if you get a period when you'd ordinarily have expected it based on your regular cycle. If there is an issue after that time, I'd consult your doctor.
Lots of things can delay a period from stress, to changes in routine, hormonal issues, slow thyroid, etc.