After ten plus years of PD, and many many many more years of living, I think I can call myself a veteran.
I was lucky, I was 58 before I began to suspect that my years of frequent stumbles over the smallest of pebbles and my strange stiffness were more than just clumsiness.
It is totally outrageous when young people get PD - it makes me furious. It just should not happen. My experience is of course not very similar to yours, who are young, but I do have some practical advice.
First of all GO VERY VERY SLOWLY with the medicines, not just sinemet but also the agonists and everything else. If you take too much, too many, too fast you will get worse very quickly, and you will not know if it is the illness or the medicine that is making you feel worse, nor willl you know which medicine is making your symptoms worse.
One of the 'advantages' of being an older PD'er is that I don't expect to feel perfectly chipper anyway. You have all the right in the world to demand a feeling of wellness and health, but PD extinguishes that expectation. I can accept that more easily than the young, so it has been easy for me to go slowly with the medicines. But if you do demand complete, though temporary near perfect movement, you are more likely to try much medicine too fast. DON'T do it.

Second piece of advice: Read all the posts about alternative ways of alleviating symptoms. Exercise, healthy diet, etc. etc.
Become knowledgeable about PD. Fight back with much more than medicine.

I am so sorry you must be here, but you are most sincerely welcome amongst us.

all the best
birte