How to Improve my ACT score

Hi everyone,

I am taking the ACT in april. On my practice tests my scores for reading, writing, and science are fluctuating a lot. Like from around 24/25-31/32. Is it maybe because I am using different books. My math score has remained between 34/35.

Also, I go to a very competitive school and almost everybody has over a 2200 on the SAT or the ACT equivalent.
How can I improve my score to a consistent 34+ in all of the categories.

I have spring break next so I will just be studying all next week. I have these books:
The Red Book(almost done)
Kaplan
Cracking the SAT: PR (almost done)
Barrons 36
McGrawHill English, reading writing(almost done)
ACT Reading by Erica Meltzer
Are there any other books I should do?
Any suggestions are welcome.

How did you do? Was Spring Break enough for studying? I have my test in a week so I am curious.