It's just like school...you learn it, memorize it for as long as you need it, and then you forget it with time. But you should have become familiar enough with the subject (as well as learned how to learn), that if you ever needed it again you should be able to Google or pick up a textbook and relearn it much more quickly then you did the first time around. THe thing you really carry away is an insight into things in general and a way of thinking about things. It's hard to quantify, but the more things you learn the more quickly you can learn other things.
In Canada, engineers are required by law to keep a dated logbook for the projects we are working on. It is a legal document and contains all your chicken scratching, doodles, notes, results, and calculations. Other things can be written down in it as well, but we don't sit around cataloging every new thing we learned in our own textbook. THat's a waste of time and that's why textbooks exist. It takes a lot of effort to document an explanations about something.
Also consider that if you make your own textbook, you are more likely to preserve the mistakes and misconceptiosn you made when learning how something worked the first time around. Textbooks are (hopefully!) written by people much more knowedgable in the subject than you are, and are less likely to make those mistakes, and also might teach the things differently to provide more insign and leave space to allow an extension into other more advanced explanations. Teaching is the practice of telling smaller and smaller lies, after all. Every time you relearn the material, you learn something new and gain more insight into it. With your own textbook, you might stagnate, gaining nothing extra every time you run back to it.
So no, I don't think it's a good idea. It's better to build up a well selected library. Also, remember that you are only second year so far and have not been exposed to very many things yet. Every single thing you just listed becomes almost inherent by the time you graduate (if you actually have an interest in EE).
Wait until you actually know how much you don't know.