I used the official teas prep book. ATI TEAS Review Manual: Sixth Edition Revised https://www.amazon.com/dp/1565335759/ref=cm_sw_r_cp_api_i_59mKFbDXAEYK0
Paid for nursehub.com and did a bunch of practice tests.
Pocket prep for the teas is also a good resource, especially for doing a few questions every night on your phone.
I also suck at tests like this. Did really well in all of the pre reqs, but got a 79 on the teas. Made me have to move to an area with a program that was more gpa based and less teas.
This is the official one. I used the same one (for the 5) and did quite well. Looks like you can get a used copy for under $20.
ATI TEAS Review Manual: Sixth Edition Revised 6th Edition
This is the OFFICIAL ONE, made by the test creator, ATI. All the rest are other companies making their own.