Yeah it’s probably because you are unfamiliar with AAMC style. This happened to me. I was getting 70-73% correct with Next Step and Altius materials then took AAMC sample and got 55%. Since then I’ve started Khan Academy CARS since people say they resemble AAMC. And they actually do. Question pack volume 1 is supposedly rough but since doing Khan Academy CARS I’ve been getting 70% right on Q bank 1 so far. The style of questions are totally different. Once you do Khan Academy and Q banks you should be good.
Your scores look generally solid like you said, except for CARS. With one month remaining, your plan seems sound: focus on CARS and take another FL in 2 weeks to see where you stand. If you haven't improved at that point by at least 3-4 points, I would consider postponing.
