Efficient improvement at ~1500 Blitz

Hey chess.com community,

I recently picked up chess again as a hobby that I would like to spend more time on. During my teens I have been playing in a club for some years up to a rating of ~1500, but due to university I became a less active player. My time is still quite limited, so I want to use it in the most efficient way for improvement.

Since recommendations should depend on the individual, I'll provide you with some information about me in the hopes that maybe someone that has been in a similar situation will read this thread and give some advice ^^ 

Openings: I usually play the London System (as White), Pirc Defense (as Black, against 1. e4), Gruenfeld/King's Indian (as Black, against 1. d4 and pretty much everything else). Recently I have started to study some opening theory and read some in-depth literature about these openings. My impression is that there definitely is a pay-off, however there are things that I do not quite fully understand yet. Also I wonder how much time I should spend on memorizing move orders which seems useful for Blitz, but for higher time controls it should be more important to know about the plans, shouldn't it?

Middlegame: I generally would say I play quite conservative and positionally. My eye for tactics is not as skilled as I would like it and I am definitely looking for ways to improve on that. Also I recently eyed up some courses about certain structures regarding my opening repertoire and generally important ones, in particular the Karlsbad structure. 

Endgame: Just basic knowledge here up to the point of playing endgames with more pawns on board. I have considered working through Silman's endgame course (book). Generally I would consider this the most important, since I play openings that will result in endgames.

I own a database program called ChessStudio on my iPad, which serves it's functionality pretty well and I do not really want to invest into ChessBase as it is a lot of money and most likely not important for my current level. Primarily I use it to go through literature, as well as analyze some games. Regarding chess content, I watch ChessNetwork (from the start, I find his content highly inspiring), Hanging Pawns (for his opening theory and some games) and TheBigGreek as well as top tournaments (for entertainment mostly). The chess content jungle is huge and if any of you have some recommendations, that would also be appreciated!

Thank you for reading through my thread, any discussion is appreciated!

~ Valky