Are you in the UK? I'm assuming so as you're measuring in pmol...
We can't accurately measure progesterone, here. We can only measure progesterone accurately in women not taking oral progesterone. This is because the test we use inaccurately identifies all these progesterone metabolites as 'progesterone' and so it comes back wrongly high.
The test we need is the LC MS P test, which isn't available on the NHS. I haven't found somewhere privately that does it either, although there might be.
Really, we can only go by symptoms. If we get unscheduled bleeding or other symptoms which might suggest low progesterone, we can increase. And if we increase our estrogen and want to be extra protected, yes, we can increase progesterone. There's nothing to lose from increasing it, if you don't get the progesterone side effects some women complain about.
I really really really x20 doubt that you are getting an estrogen level of 945pmol from 1mg of Sandrena. That is the equivalent of 2 pumps of gel. You would need to be an amazing absorber of estrogen to be getting that much. I've never heard of it. What is WAAAAAYYY more likely is your ovaries pumped out some extra estrogen when you tested - OR that your test site (finger prick? venous?) was contaminated with some gel. Do you apply it to arms or only to legs?