I was wondering is it drug abuse if I take non prescribed medication every time I can?

If 1) you bought it over the counter, 2) it's not someone else's prescription, 3) it's not a prescription you are taking more often than you were told to, 4) you take it because you need it and it solves the problem that you wanted it to solve, and 5) you don't take more than the recommended dose, it is not abuse.

If the drug is illegal, prescribed to someone else, prescribed to you but taken more often than directed, taken in larger quantities than recommended, or used recreationally (for fun as opposed to filling a need), then it is technically drug abuse.

Whether or not drug abuse is actually harmful is another question entirely, which depends on the drug, your age, your health, the doseage, and various other factors (and even after that, the conclusion may still be a controversial one). For example, I know a lot of people who take an extra pain killer over the recommended dose (only when they need the pain killer to begin with), which is technically drug abuse, but they suffer no real negative consequences. People who do illegal drugs in high doses just because they like the mental/emotional side effects, however, usually do serious damage to their bodies.

So whether you are abusing drugs is pretty clear, but whether it is a problem can get complicated. If unsure, avoid abusing them at all.