Hi Bggio (Dean),
Firstly let me say I could be out of my depth here, so I'm not advising, merely commenting.
I do however find it difficult to believe the level of medication you are on after just 2 years. As for being underdosed, again it is difficult to get my head round that.
Madopar is levedopa with the agonist Benserazide. Stelevo is carbidopa and levedopa with entacapone (a commit inhibitor). Sinemet contains levedopa plus carbidopa
That means you are taking nearly 1,000 mg of levedopa plus inbuilt agonists daily.
I don't know what Pregablin, Sertraline or Furosamide do? I would go on the Parkinson site and check.
There are ways of obtaining a second opinion and maybe our moderator could help or advise you.
As you probably know Parkinson's symptoms vary enormously. Also side effects of medication.
I do so hope some review is possible and things improve for you.