For most people, including myself, there is pretty much no chance that you’ll remember most of the things you’ll see and do in math-land the first time ‘round. It’s just an inevitable relic of the fact that mathematics is... well... hard, and it isn’t something that the human brain was designed to do. The fact that you’ve gotten as far as you have is an accomplishment you should be proud of. You’ve already bridged the statistical gap!
But, as you’ve clearly realized, mathematics is easily the farthest thing from a spectator sport. It gets easier, but there are always going to be challenges, that’s part of the fun. Anyway, back to the point: Math is hard to learn, and even harder to remember. How do you do it right? Take good notes!
I can’t stress how important this really is. I take notes as if I was to forget everything the next day, because chances are I will. The better the notes, the more of the material will fall into place every time you go over it. Every time you go over stuff, add your immediate conclusions and thoughts. In this sense, you will be building up a better and better “imprint” of your own brain’s critical response to the material.
Frame it in your own language, draw pictures, whatever you need to do, just make sure you’ve done everything correctly and that you haven’t sacrificed any of the concept in exchange for intuition. Intuition is great, but not for definitions. The whole point of math is to create a more functional, tangible language to describe things, and watch how the intuition unfolds. Not the other way around.
However, us humans aren’t perfect, optimal and all-knowing holders of ultimate truth and beauty, we have the slightly more disappointing form of a messy set of poorly-calibrated neural networks that are really only capable of expanding conceptually on the relatively basic patterns that only arise after many years of consistent experiences. So the only reason we have wildly brilliant people like Dirac, Einstein, and Ramanujan among us is the fact that they were masters of framing mathematics, more-or-less, in terms of basic experience and intuition. So, as cheesy as I know this is going to sound, “The answer lies within YOU.” Only you know what you understand better than anything else. So, whatever that thing is for you, find it, because it’s going to be the most effective thing you’ll ever be able to use as an analogy.
TL;DR: Mathematics is a beautiful subject, and the best way to learn it is to relate it to what you find to be your own core experiences.