That's an interesting group of words there. I don't think に ever goes with 比較的, though. I remember having that point driven home by teachers.
連合軍 is so specialized it's not even worth worrying about all that much. How often are you talking about the Allied Forces?
As far as 判断 goes, what's the problem? Are you unsure of when to use it versus 判定, for example?
At any rate, I think the answer to this is simply exposure. Keep listening to NHK news. Keep watching movies and TV shows. Also listen to and read along with
ANNニュース. Read a lot. Make sure you're being exposed to the language nearly constantly.
About reading: there are two ways to do it, generally speaking. There's the look-up-every-word-you-don't-understand way, and the reading to read way, where you don't worry about not understanding everything so much. They're both important, so do them both. Try to stick to things that are accessible in length, familiarity of vocabulary, and difficulty, but also push yourself and don't just pick overly simple material. And don't worry about not finishing. What you get out of it is important, not whether you finish. If what you're aiming to get out of it is an exercise in reading speed, get as much as you can out of that. If what you're trying to get out of it is a deeper understanding of the grammar and word usage, get as much as you can out of that. Remember what your goals are and why you started reading in the first place.
I think if you combine all of these approaches, you should start seeing appreciable results in a few months. If you're worried about forgetting the stuff you've learned, use an SRS like
Anki. Also, keep talking to that exchange student. You can learn a lot from her as well, and it should keep you motivated.