Medication troubles

Has anyone else here found that the meds they're on for the ADHD seemed to stop working as well for you?  

I don't think my Concerta's working as well for me anymore.   Many days I find myself wondering if I even took it because I can't focus or stay on task, fidget, am more sensitive to sensory overload and seem to get just as irritable as when I forget it.   

The only way I know I've taken it these days is my appetite cause that side effect is still working, and a little too well too.  I've been losing weight and having a hard time putting it on.   I'm actually underweight right now.  

My PCP has expressed concern about my decreasing weight the last few months and said if I can't gain weight it might be time to change meds to one that won't affect my appetite as much.  At first I kinda balked but when I thought about it honestly I realized the Concerta's just not as effective for me anymore.   

I don't enjoy the thought of having to go through trial and error to see what other things work, but it's necessary as I want to be able to focus and I don't want to lose anymore weight.