I have a feeling you are selling yourself short (and being overly hard on yourself, something I'm well acquainted with but more easily recognize in others).

Based on your technical focus, you're clearly (in my opinion) way above the "average" developer in technical ambition and appreciation for computer science.

A bit of unsolicited advice: If you organize your preparations around the concept of providing value to a prospective employer, rather than merely getting hired to write code, then I bet your outlook will change. One book (and definitely not the only one) that can help with that is Bob Martin's The Clean Coder: A Code of Conduct for Professional Programmers:

https://www.amazon.com/Clean-Coder-Conduct-Professional-Prog...

I've gathered all the book titles in this thread and created Amazon affiliate links (if you don't mind. Otherwise you still have all the titles together :-) )

A Pattern Language, Alexander and Ishikawa and Silverstein http://amzn.to/2s9aSSc

Advanced Programming in the Unix Environment , Stevens http://amzn.to/2qPOMjN

Algorithmics: the Spirit of Computing, Harel http://amzn.to/2rW5FNS

Applied Crytography, Wiley http://amzn.to/2rsULxS

Clean Code, Martin http://amzn.to/2sIOWtQ

Clean Coder, Martin http://amzn.to/2rWgbEP

Code Complete, McConnel http://amzn.to/2qSUIwE

Code: The Hidden Language of Computer Hardware and Software, Petzold http://amzn.to/2rWfR9d

Coders at Work, Seibel http://amzn.to/2qPCasZ

Compilers: Principles, Techniques, & Tools, Aho http://amzn.to/2rCSUVA

Computer Systems: A Programmer's Perspective, O'Hallaron and Bryant http://amzn.to/2qPY5jH

Data Flow Analysis: Theory and Practice, Khedker http://amzn.to/2qTnSvr

Dependency Injection in .NET, Seemann http://amzn.to/2rCz0tV

Domain Driven Design, Evans http://amzn.to/2sIGM4N

Fundamentals of Wireless Communication, Tse and Viswanath http://amzn.to/2rCTmTM

Genetic Programming: An Intrduction, Banzhaf http://amzn.to/2s9sdut

Head First Design Patterns, O'Reilly http://amzn.to/2rCISUB

Implementing Domain-Driven Design, Vernon http://amzn.to/2qQ2G5u

Intrduction to Algorithms, CLRS http://amzn.to/2qXmSBU

Introduction to General Systems Thinking, Weinberg http://amzn.to/2qTuGJw

Joy of Clojure, Fogus and Houser http://amzn.to/2qPL4qr

Let over Lambda, Hoyte http://amzn.to/2rWljcp

Operating Systems: Design and Implementation, Tanenbaum http://amzn.to/2rKudsw

Parsing Techniques, Grune and Jacobs http://amzn.to/2rKNXfn

Peopleware: Productive Projects and Teams, DeMarco and Lister http://amzn.to/2qTu86F

Programming Pearls, Bentley http://amzn.to/2sIRPe9

Software Process Design: Out of the Tar Pit, McGraw-Hill http://amzn.to/2rVX0v0

Software Runaways, Glass http://amzn.to/2qT2mHn

Sorting and Searching, Knuth http://amzn.to/2qQ4NWQ

Structure and Interpretation of Computer Programs, Abelson and Sussman http://amzn.to/2qTflsk

The Art of Unit Testing, Manning http://amzn.to/2rsERDu

The Art of Unix Programming, ESR http://amzn.to/2sIAXUZ

The Design of Design: Essays from a Computer Scientist, Brooks http://amzn.to/2rsPjev

The Effective Engineer, Lau http://amzn.to/2s9fY0X

The Elements of Style, Strunk and White http://amzn.to/2svB3Qz

The Healthy Programmer, Kutner http://amzn.to/2qQ2MtQ

The Linux Programming Interface, Kerrisk http://amzn.to/2rsF8Xi

The Mythical Man-Month, Brooks http://amzn.to/2rt0dAR

The Practice of Programming, Kernighan and Pike http://amzn.to/2qTje0C

The Pragmatic Programmer, Hunt and Thomas http://amzn.to/2s9dlvS

The Psychology of Computer Programming, Weinberg http://amzn.to/2rsPypy

Transaction Processing: Concepts and Techniques, Gray and Reuter http://amzn.to/

Types and Programming Languages, Pierce http://amzn.to/2qT2d6G

Understanding MySQL Internals, Pachev http://amzn.to/2svXuFo

Working Effectively with Legacy Code, Feathers http://amzn.to/2sIr09R

Zen of graphics programming, Abrash http://amzn.to/2rKIW6Q