Estrone converts weakly to estradiol so don't expect much from estrone. Levels will spike rapidly with sublingual, perhaps not as rapidly with buccal but due to fluctuations of level in time, levels can be misleading. Instead focus on physical results (i.e. feminization, breast growth) and how you feel, these will let you know if you are on the right dose for YOU.

I wouldn't advise medroxyprogesterone acetate as it has been associated with breast cancer, vascular/clotting problems, can trigger depression in some, even up to suicidal tendencies and is mildly androgenic (triggers androgen receptors). Several studies, like SEVERAL, have shown how harmful it can potentially be to the human body. It also won't increase progesterone levels as it does not metabolize to progesterone, the hormone produced naturally in our bodies.
I'm not a doctor. I am basing myself on studies alone. You could perhaps ask the doctor to switch you to a safer progestogen such as progesterone (Prometrium).