Yes, "stuck with" was the wrong choice. If you're stuck with something it means you have it but you don't want it or you wish you didn't have it. You can be "stuck on" a question in a test.
Helen: How are you getting on with your homework?
George: Not too bad, but I'm completely stuck on question 10.
In your context, I'd just say "I'm confused about/I don't know whether I should use sport or sports in the following sentence".