Official guidelines recommend using the same dose vaginally as you have been prescribed orally, however there is limited evidence that it has a more potent and targeted effect on the endometrium when taken vaginally.
This makes biological sense for two reasons, one is the idea of a first pass effect, in that it is taken up preferentially by the uterus and surrounding blood vessels due to anatomical proximity, and secondly the fact that when taken by mouth it largely gets converted to other metabolites such as allopregnanolone, with relatively little actual progesterone entering the systemic circulation.
There is more published evidence to support the latter, however I believe it is a combination of both and possibly other unknown mechanisms.
As you are looking for a more potent effect, and also because I cannot recommend reducing your dose unless you are under a specialist and being monitored, I would suggest using your current dose vaginally and seeing if this has the desired effect.
There is also one small study indicating that vaginal progesterone doesn't antagonise the vascular benefits of estrogen in the same way that oral does.