I have been on Concerta for about 2 and half weeks. For the first week and few days I was taking 18mg/day. I was barely feeling any effects and was having no side effects. I called my doctor and she had me go up to 36mg/day.
Now I am not feeling any different than I was on 18mg/day. Still have a very short attention span, am easily distracted from doing things that I want/need to do, and find it really difficult listen to someone speaking to me without my mind drifing off. And still no side effects and no problems sleeping. I can tell when the Concerta wears off and think that once we have found the right dose I will ask for some regular Ritalin that I can take late afternoon/early night to cover those hours after the Concerta wears off.

So, the big question is: When do I know I am taking enough? Will I suddenly feel that I can concentrate on a single thing at a time? Should I keep increasing the dose until I have some negative side effects and then drop down to the last dosage?

I have been wondering the same thing I was on Ritalin 10mg 3 times a day forever and when I felt it wasnt working anymore my dock put me on Concerta 36mg/day and I tried it for a month almost and I told my doc it wasnt helping and wanted to try a different med but he said he wanted to go up on the dose so I have been tring Concerta 54mg/day for almost a month and I still feel lost I dont see any difference at all I did take a Concerta 36mg and 54mg one day by misstake and it seemed to help a little bit but I dont want to have to take that much meds a day I would rather try Adderall to see if it might help

Is anything easier for you with the medication?

At 36mg/day it is slightly easier to concentrate and listen to others, but it is so slight I can't say that it is nothing more that a placebo effect. I am still distracted very easily and most of the time thinking of something else when I am doing something or listening to someone.