So, I know that 50s on Uworld supposedly correlates to around low 200's, but I think this can only be considered accurate if you are doing it on random, timed mode. It is not the same to have just gone over a topic in FA and pathoma and then do questions on that specific topic. Even if you haven't just done corresponding chapters, doing qbanks on subject mode gives you an advantage you won't have in random. But, regardless of whether your Uworld is an accurate assessment, the NBME is the most valuable predictor.
The problems I'm feeling with your methods right now are:
1) You are taking too long to do things/you haven't done much. I know you haven't been in dedicated mode yet, but when you said you had been studying since January, I was worried. Now it sounds more like you haven't done a whole lot of board studying, and at such a slow pace over such a long time it is hard to build up momentum. It is likely you haven't retained much of what you did 3 months ago.
2) You need to start memorizing things. A quick first pass of FA where you don't try and drill every little detail in is ok--but a "quick" first pass of uworld, FA, and pathoma won't be quick or productive. You need to be learning as you are going. I use anki to drill in the discrete facts I miss in qbanks, and I can tell it is working because my scores are improving, and now I'll get questions over topics I've drilled into my head that I would've gotten wrong 2 months ago. Learn as you go, drill things in as necessary; don't just expect to learn by osmosis.
3) Maybe you should think about doing timed, random mode on Uworld. I know there are people who use tutor mode almost exclusively and they do just fine. I personally give a lot more thought to the question when I'm not going to get an immediate answer. I have a chance to flag things I'm not sure of and go back in my last 5 minutes and rack my brain over it, because I don't want to see a below average percentage on that block, and when I get something wrong I labored over in my head it sticks with me a lot better and helps identify weaknesses. Also, by the time I sit for the boards I will have done around 150 46question/hour blocks. Hopefully it won't feel like anything new on the real thing. I especially recommend this if you had any issues with timing on your NBME.