It is important to record your observations and the observations of others and see your doctor for a review. Everyone is different. However, don’t jump to conclusions or make changes to medications on your own without the advice of your doctor.
The medications are not necessarily related to weight. For example, certain people have what is called slow metabolizing livers so that the amount they need is much less than the average person. It is not common but if you are one of those people, taking the same dose as your friend might put you over the top. Look at my video on Compliance for some helpful hints.
But…..talk to your doc.