Do take the ACT.
It’s possible to increase by +30, perhaps +50 in 4 weeks.
A high CR score comes from reading daily and ever since you’ve been able to, not just for school, and including fiction AND non fiction AS WELL AS magazine articles (for example, from the New Yorker, the Atlantic, Mother Jones, The National Review, The Economist, Harper’s… at least one article a week. Obviously, one a week for 3 or 4 years won’t work here, but you can try to compensate by reading one per day?)
So, focus on reading one high-level magazine article per day, alternating between the magazines above (they represent different traditions and styles, and a couple are sure to be provocative to you) from your local library. That should be 25+ articles… not perfect to build fluency and critical reading skills, but it’s hard to do more.