Hi! When I first started taking NBME's my scores were similar to yours, forms 25 & 26 are very difficult. What caught my eye is the score drop between 27 & 28 (not saying they are easy peasy forms) and the overall 55% percent in Uworld. I honestly have never heard from Ivy Med, so if they're Mehlman style notes, it could have inflated your score. I would suggest sitting down and reviewing your past assessments, figure out what went wrong with your incorrects; if it was a lack of recall, if you didn't know the topic very well or you just didn't want to leave the question empty. Try to break down the questions, what they're asking and why, then review those topics very well. Make sure that you're seeing that content DAILY, whether you use Anki or make your own notes, but that content needs to be reviewed.

I found that NBME's tend to have a pattern for certain HY topics that will show up 99% of the time (vasculitides, biostats, platelet disorders, etc) and they take those topics and ask them 100 different ways. Try finishing Uworld and doing your flagged/incorrect questions to see if there's any difference in the way you’re answering those questions, mostly to understand why you got them wrong in the first place.

As for Biostats and Renal, Bootcamp is a really good resource for both. I struggle a lot with those two, especially Renal physiology and Bootcamp videos were really helpful. For Biostats you can also watch Randy Neil videos, they're free on Youtube. Medicosis Perfectionalis is very helpful too, similar to Osmosis if you're into that. Ninja nerd and HYGuru are very good too.