How do I improve my coursework?

It depends what you define as "bad." Your level of course rigor is excellent, so I don't think it's that. You're really only supposed to put the number of advanced courses and not your regular courses. College Vine should probably say that "Your course rigor is excellent" or something similar in the course rigor section of your Chancing. What I think is happening is that you're looking at Ivy's or other schools with super-low acceptance rates and assuming that your chances are low (probably <25%) because of your profile when it's actually because everyone's chances are low at these long reach schools, even people with course rigor as great as yours. Make sure you have a balanced school list and don't just apply for extremely prestigious schools. Find some schools that have a higher acceptance rate and sufficient financial aid for your family, where you would still be happy attending. Hope this helped!

The amount of IB classes you are taking is impressive so I think it's safe to assume that it's because you can't input all of your classes. If you also want to increase your chances even more, colleges love the amount of time you put into your school and community, things like clubs and community service would help.