We are heading into Plumeria sleep time as winter ensues some more...just got to keep them dry, no watering. Looking at your media, it really needs to be much grittier than that if you really intend to keep it awake if you can this winter. But, if it does go dormant, while it is dormant this winter, you can improve that, add much more pumice or perlite. So when Spring comes around, the plant will wake up much better with a much more well draining media.
Just to give you an idea, this is how gritty my Plumeria media is:
June 2017 file photo
as you can see, like all my typical succulents, they are all planted likewise in a gritty well draining media. Plumeria on this photo is finally waking up from its winter slumber. Took a long time, really wants warm to hot temps. So in winter, with lighting not sufficient, and temps cooler all over, it will just sleep it out, and wait for late Spring to Summer to wake up again:
