Should I focus on my grades or on finishing my degree on time?
Usually there is a scheduled time and an expected number of credits for a degree. A BSc normally takes 4 years, with a given number of classes. This is because the ability to absorb the material in the allotted time is part of the evaluation of the student. 

Ordinarily that is. But you mention health issues.

If you had some major life altering illness then it is something you should discuss with the university. I mean something like as serious as pneumonia. I had pneumonia a couple years ago. If it had happened in university it would certainly have cost me a term, maybe a full year. 

Under such circumstances, and presuming you now have some kind of control of the situation, you should consider repeating either a term or a year, depending. 

First talk to your favorite prof or your department chair. Ask if there is the possibility of repeating the year. Or possibly repeating only some of the classes. In most cases, they will want to help you. It looks good for them for you to perform well in the university. They will nearly always want to help you finish the degree.

Be open to their suggestions. They may have suggestions of alternatives.