If you have a cycle of 39-40 days, you should still ovulate 14 days before that in theory. Can you count back and remember if you DTD on that date roughly? It might give you an indicator of if you are pg or not. Usually symptoms don't start appearing until after implantation, but I have noticed that I do feel different to when AF is coming kwim? So not pg symptoms as such but just feeling different.

Also don't be worried by the lack of symptoms cause not everyone will get strong signs of m/s etc. It is possible that you have had an implantation bleed if your AF is not due for a few days.

Good luck and let us know how you go.