How to raise your level of English?

Question

English learning tools

Good day!
I stubbornly study programming languages, but I understand that technical knowledge alone is not limited.
Briefly about my level of English: I can read quickly with an understanding of 80-90% of what I read, a good vocabulary, but a very big problem with grammar.
Advise how to be in order to raise your level of English to the level of Upper intermediate at least in 2 years.
Preferably a good book.
Thank you very much in advance for your advice.

Answer 1

Essential Grammar In Use

Answer 2

the book will not raise upper intermediate for you, because this level assumes fairly fluent speaking and listening skills.
So practice is more than MANDATORY. Even more obligatory than good grammar.

Answer 3

You can start with the same LinguaLeo. There are quite normal grammar courses.

Answer 4

I can read quickly with an understanding of 80-90%

I'm pretty sure you're flattering yourself. You shouldn't be doing this. It is better to underestimate this estimate than to overestimate it.
Answering the question about grammar - read. Read a lot. Not a book ( OMG, a whole book?! ), but books. Those. you can, of course, try to memorize the rules, but without a large layer of real use of these rules, it will not linger in your head for a long time. In short, read maniac.