I am also taking it on July 18th and I am on the same boat as you, except I've take Organic I and II. I got Dr. Collins and am in the process of memorizing then understanding everything I can on the Biology section. I also have the Kaplan book and as I compare by subsection(Nervous System, etc.) the information in the Kaplan book vs Dr. Collins, Dr. Collins keeps it simple and short. Whereas the Kaplan book goes into much detail, which I think is somewhat wasting my time. Anyways, I would recommend getting Dr. Collins and do whatever you feel like, don't let the thought of "I'm taking the PCAT, what do I do if I do bad?" keep you from fully studying and understand the concepts. Study what the website says, and you will do just fine. It's not like the website is telling you what concepts will be covered on the exam and then asking the completely opposite concepts.