I've had this discussion with my PCP more than once. He says that physical dependence is worlds away from addiction. An addict will continue using a substance even when they are aware that it will harm them or the way they live their life. So, I think the previous poster is right on - does the drug control you, or do you control the drug? If you are able to stay within the prescribed amount, then you are probably not an addict.
On the other hand, dependence has to do with body chemistry.
You can be physically dependent on high blood pressure medication, heart medication, or anti-depressants. Your brain gets used to having the substance and reacts, sometimes violently, if the substance is suddenly withdrawn. My doctor told me that a patient should never just "stop" taking something that has been prescribed for a long period of time. It essentially causes a trauma to the part of the brain or body where it works.