Learning music theory or just music in general is like learning another language. As you’ve seen with languages, there are so many gimmicks promising to teach you to speak that language in 10 days, etc….
As you know, this just doesn’t happen. To speak a language takes time and most importantly, practice. You have to take the basics and apply those by speaking with someone who knows the language well. Until you apply it, it is sort of useless.
Add on top of that, learning this language as an adult which slows the process. As children, we pick it up with no trouble. As adults with busy schedules, we have to be extremely disciplined.
Music takes years to learn, not just a few months. Learning the basics of music theory is easy. But when you apply it and start to practice it, putting all of these elements together, you realize the difficulty of the task. I encourage you to not beat yourself up so much. Realize that this process is a long one. Take it step by step and practice in short time segments. Even five minutes consistently every day will bring results over time.
Don’t give up! Don’t fall for the short term promises. Make this a journey which will bring you such joy as music is our universal language.