Is the 51 your percentile score or is it your % correct? If % correct, that's a little more concerning, if it's percentile, I wouldn't worry too much about it.
Honestly, my advice would be to streamline and consolidate your content review studying and do more questions. Ultimately, how well you're doing on the Qbank is somewhat meaningless. UWorld has about 2600 questions for Step 1 (maybe more now, idk) - I would try to do like 5000+ total questions in lieu of reading FA super in depth. Do new, marked, and incorrect questions frequently. I also agree with taking an NBME practice test ASAP to see where you are, then taking at least one per week for the remainder of your dedicated period.
If you get the answer right and feel pretty good about it, I would just read the learning point at the end of the explanation, and go on to the next question. No point reading about something you already know. If you get a question wrong or got it right on a guess, then consider reading more of the answer explanation.
IMO, spending time doing more questions is a better use of time than doing fewer questions and reading the explanations / First Aid more thoroughly. You'll address a lot of your weak areas by doing questions and you'll likely retain it better by doing questions than by reading FA/etc.
I think that Pathoma is great as a supplement - watch the lectures at 1.5x+ speed while looking at the book and making light annotations, especially in weak areas. Sketchy micro (ONLY bacteria - the rest are not high yield enough for the actual test) is great for bacteria and antibiotics. I would use First Aid pretty much only as a reference and not as a textbook that you read cover to cover. Use Anki for one off facts that you just need to remember and retain (like CD markings, drug side effects, causes of TTP, whatever), but use it judiciously. UWorld should really be the primary resource.
UFAP works for a reason, with the U by far being the most important. It's very possible to get bogged down with too many resources. UWorld + frequent practice tests will be the most efficient way to study by far. Doing 5-6k UWorld questions + FA + Pathoma + sketchy + minimal Anki bumped my score >70 points in 7 weeks of dedicated, and UWorld was by far the most valuable resource.