My understanding is that the lowest dose often is not enough. You probably did a number of questionnaires before his diagnosis that output a score. There are also follow up forms that help decide if the med is working or not. Also, I would think at 13, DS should be able to have an idea of whether they are working (combined with what you see behaviorally, grades, etc.)
You may be able to call and ask for a higher dose on a trial basis. In addition, if his weight becomes an issue, there are other types of drugs that may work without affecting hunger as much. I have been told that these can work differently on different individuals. You also may want to ask if you can skip pills on weekends.
That all being said, I would address your concerns with the prescriber, or whoever is in charge of doing the refills.
