Thanks, mate 🙂
You seem to be on the right track. You will usually score a bit higher on the NBME4/6 that you do secondly, due to the overlap. NBME7 and UWSA are wisely saved for the end.
At first glance, your plan seemed ambitious, but then seeing that you have already gone through UWorld a few times, it is absolutely fine. However, I am wondering whether you are doing all the questions once again or just the marked/incorrect, etc.?
I have not read First Aid (I only skimmed through the one for step 2 CK and did not like the format, and I have not yet taken step 1), so I personally would not know whether it is helpful for Psych, but a lot of people rely on FA step 1 for step 2 CK as well. UWorld and CMS were more than enough for me, I honestly think I got all those questions correct.
However, that being said, when you are this close to the exam, it is a fair move to take care of your insecurities, regardless of the resources you believe in. If you enter the exam room confidently, you will surely give a better performance. The glycogen storage diseases are low yield, but then again, if you have sat step 1, you can probably go over them in no time, and it will reduce your anxiety level.
I would recommend going through these self-perceived weak areas as soon as possible, because the closer you are to the exam, the less likely you are to remember dry facts. The last couple of days are just to keep momentum and stamina and perhaps go through a few high yield subjects. The very last day should be a day (or at least half a day) off. What are the odds that you will read something that shows up word for word on the test? By this time, you know what you need to know. It is all about optimizing your cognitive function. Think of it as a marathon. You wouldn’t run a marathon the day before, but perhaps a slow 5K.