Ask, all I know about progesterone is that it's a measure of whether you've ovulated or not. So when I had my progesterone measured not on Clomid, it was low because I didn't ovulate. But when I was on Clomid and I ovulated, my progesterone was high.
For women with PCOS, even when they ovulate, often their progesterone will rise but drop quite suddenly, which doesn't help when you want to sustain a pregnancy. On the cycle I conceived my progesterone was 34 I think. At 12 DPO it was 80 something and it rose again at 15 DPO. So thankfully, I didn't need progesterone.
I think we can conclude that you ovulate Ask, your progesterone must be high enough then. But perhaps it drops quickly after? You can buy natural progesterone cream which is meant to help.
I don't know if that's any help. For me, progesterone makes my PCOS worse. During my TWW (on Clomid) I always felt rubbish and I can definitely tell throughout this pregnancy when progesterone is high (and estrogen is low). If your doctor won't test it, either find a new doctor or maybe try natural progesterone.
A side note, please be very careful about taking Vitex when you have a normal cycle. It can make things worse and you may even stop ovulating or develop very irregular cycles.