The reality is the Sinamet is not a perfect solution. It takes time to absorb in your body and then may wear off before the next dose is due. Try to monitor your doses to determine when its most effective and plan you activities accordingly. In my case I try to take my first dose on an empty stomach because it is sometimes slightly more effective for me. But if that upsets your stomach, take it with a meal. My meds take about 60 minutes to be most effective so if I have a social event I time that dose accordingly. It's not a perfect science but work with it to get the best outcome for you. My wife also has Parkinson's and I live by her quote, Don't wait for the storm to pass, learn to dance in the rain.
Best wishes, Joe