I literally made an account just to respond to this thread lol.
I know exactly how you feel. I am in my fourth year of Biomedical Science and I am applying for law school right now. My parents really pushed me into medicine because they felt it was best and even though I didn't necessarily enjoy the sciences but I was good at it so I just went with it. Nevermind that initially I wanted to study political science. My parents did not really see the value in an arts degree so that secured me fate. And what I was worried would happen, happened. I am guessing this may be what you are going through too. It was really hard to fake interest. I was surrounded by all these people who really wanted to be there, who were dead set on professional school and really enjoyed the courses we were taking. And yet I felt indifferent at best.
I decided to pursue law after a heated discussion with my parents in third year after telling them medicine was not for me. And at that point it was way too late to change my major so I just decided I'd power through it.
What I wanted to tell you is that firstly, whatever degree you get whether political science or science, it will never be a waste of time. Even if you don't end up going into an adjacent field. But if you do want to do a post grad (whether law school, med school, dent school, optom etc) and you know that your grades will not be that high because of your major, I would consider switching. Because looking at it realistically, to get into med school in Canada you just need 1st and 2nd year bio and chem. That's literally all (maybe a few additional courses depending on the school). I have a friend with a history degree who got into UofT medicine just cause he took the prerequisites. A science degree is not the only way to professional school so I would encourage you to look into these a little more and find out exactly what courses you need to take. Many times you can fit them in within an art degree while using all those art courses to buffer your GPA.
And same thing with law school. They will take you with any degree. But what really opens up pathways is good grades. There's no substitute for that. If you're also scared about making such a huge jump from science to arts, consider doing an easier science or health science programs that will still keep the doors open to professional school but give you good grades if you do choose to do law school. I'm not sure what school you are at but reach out to your academic advisor about other programs in your school like general honors science, science psychology, health studies, public health, or kinesiology. Those will give you the best of both worlds!