That is a LOT of opening theory to know for that level. I got by with knowing one system for white and one defense for each against 1.e4 and 1.d4. I got away with just what I have highlighted in red. When it comes down to it, once the opening phase is done you are left with nothing but chess. From 0-2200+ (non-blitz games), the game is not won or lost in the opening, but by tactical means due to an inaccurate play by one side.
How to improve your chess


My System has a terrible information to noise ratio but is otherwise a great book. I'd also recommend Soviet Middlegame Technique by Quality Chess too.
Also 7 openings isn't enough for any level. As black you need a defense against:
-King's Gambit (2...Bc5 and 2...d5! are quite playable if one doesn't know the theory)
-Ruy Lopez (3...Bc5 and 3...Nf6 are good if 3...Nf6 4.d3 (4.Qe2) then natural moves should help. Otherwise learning the Berlin Wall and Marshall Attack are great as long as opening study doesn't interfere with middle and endgame study)
-Italian (I recommend 3...Bc5 since 3.Bc4,Nf6 4.Ng5 is quite sensitive and theoretical)
-Danish Gambit
-Scotch Game
-Something against the English (I like either a hedgehog or 1...e5)
-Something against 1.d4 ( I like the Dutch and Nimzo-Bogo Indian complexes)
And as white you'd need to face the French, Caro-Kahn, Sicilian, 1...e5, Modern, Pirc, and even the mainline Basman and 1...b6 for good measure (not allowing 1.e4,b6?! or 1.e4,g5? to be "I win" gimmicks just because they memorized more theory in them)
A weapon against 1.b3 and 1.Nc3 are optional (Caro-Kahn without the c-pawn committed is recommended against 1.Nc3 and when you move to ...c5 it'll be in one go, like a Mainline Caro-Kahn with an extra tempo!)
Agree that real chess starts out of the opening, but why leave the opponent with better chances? Berlin Wall theory and strategic endgame or queenless middlegame skill go quite well together.
The good thing about opening study is once it's done it's done (unless you take up the Najdorf, then it's a second full time job), you understand the plans, endgames, pawn structures, concrete variations, etc., that result and could focus most study on middle and endgame themes.

I agree with #3. Learn opening theory is very underrated i think
Anyway there is no secret to improve, you can get lot of good advices but finally you are on your own
People make it too complicated. Here is the secret:
Play Chess, Play chess and play more.
Number one way to improve your game.
Play players 150-200 more fide points than you.
When your finished thank your opponent for the game and see if he will talk to you maybe he has some advice.
Reviewing your opponents games is just as useful as reviewing the ones of grandmasters.
Once you've finished go through the game and if you want analyse it (prefferably through your own engine, the chess.com one, unless you have premuim membership is very very bad) do so. It will really benefit your play.
Play, play and play. The only other thing you can do is study and solve chess puzzles.
At 0-1375 level all you need to know is 6 or 7 openings, opening theory, tactical weapons, and basic strategic plans e.g. material, space, the iniative, learn basic endgames such as checkmate with queen, rook, two bishops. That's all.
For chess books I reccomend: Starting out in chess: Bryon Jacobs, Win at chess: Teach Yourself: William Hartson and My System: Aron Nimzowitsch.
Be sure to comment if my method worked for you!