Everyone is different. Some people find the meds lose effectiveness and need to be increased or changed periodically. It also may be that you have been at a dose that is barely enough and it has taken time to find that it was a little low. Another thing to consider is the posibility of stress. Stress or lack of sleep makes the brain less efficient and increases ADHD symptoms. The increase can overwhelm the positive effects of the meds. You should talk to the doc and try to sort it all out.
I have been on Ritalin 10mg x 4 a day for about a year now. I am starting to notice that I am loosing my place while I am thinking and it is more of a struggle to remember what I was talking about. When I have been out of meds, I am very aware of how severe this can be so I am familiar with the process. Can the meds loose their effectiveness or do you plateau and slide backwards? Is this an indication that an increase is needed and does this continue to happen?
Any help would be appreciated.