Since you're going to have to do your BFR, it wouldn't be a bad idea to refresh your memory with the Flight Review guide from ASA.

https://www.amazon.com/Guide-Flight-...ustomerReviews

Although I haven't used that particular one, I have found those Prep guides to be excellent for the Instrument and Commercial orals. Get a few stacks of flash cards as well to help with the questions you're having issues with.