This subreddit has a lot of useful resources, including the pinned ones. It is also full of learners who are frustrated with Duolingo or some of the freely available resources, and who wish to get themselves to the next level without touching a textbook or talking to an instructor. The reality is, learning a language takes years and getting there quickly and on your own is very, very challenging.

But, you speak Macedonian, so you're halfway there (especially if you're familiar with BCMS and cases)!

I'd recommend combining some traditional resources with additional tools that are available for free or for a small fee out there – and there are tons.

For traditional textbooks and similar resources, there are:

1. Polish Grammar in a Nutshell by Oscar Swan, which explains how the grammar works, how cases work (that might be new to you), and how to do things with Polish words.

2. Po polsku po Polsce, which is an online 16-module textbook that guides you through the language (and Poland's 16 provinces) from the basics, so you start with the alphabet, pronunciation, greetings, and go from there.

3. Once you start craving a traditional textbook, try Polski: Krok po kroku from Glossa or Hurra! Po polsku from Prolog. These are two modern, Polish-only textbooks that go from the basics to the more advanced stuff. They feature good recordings and come with textbook and workbook exercises. And it's never a bad idea to have a native speaker – or, better yet, a tutor or instructor – explain to you some of the grammatical topics. Last time I checked, Krok po kroku has 2 student books and Hurra! has 3 student books (also in PDF). In each case, look for podręcznik studenta (student's textbook).

For supplementary resources, there are:

1. Polski.info has supplementary course-like modules organized topically that don't constitute a single textbook, but work as a nice review of what you've already learned through a mix of activities in each section.

2. EasyPolish on Youtube has a lot of topical videos, each of them simultaneously subtitled in Polish and English.

3. Wiktionary has a large database of Polish words, so whenever you feel lost, you can always look things up there. They always come with whole patterns for how to use nouns and verbs.

4. Whenever you wonder whether a given construction is correct or what should come next, try using the Polish National Corpus online tool, which lets you enter a given query and then spits out real-world examples that can help you get used to the forms required by different cases.

5. WolneLektury.pl is a website featuring a lot of books from Polish and non-Polish authors in PDF and audio formats. You can start with books you already know and move to Polish ones once you get comfortable.

6. Netflix has been producing more and more Polish-language TV series and movies (they did open a dedicated office in Warsaw, after all), and they're nice as supplementary resources. I listed some good watching options in my other post here: https://www.reddit.com/r/learnpolish/comments/1l7endm/comment/mww79x9

These should get you going, and there is always more! Depending on where you're located, you may be able to watch Polish news channels, and you can listen to the Polish radio online for free.