More than one online teachers tell me not to focus on grammar so seriously. The fact is that not all native speakers are familiar with all grammar rules, but they can use English correctly and naturally. I call it grammar internalization(I am not sure if it is suitable expression). In the beginning, I needed to focus on grammar in detail, but now it seems that I have already forgotten some of grammar, on the other words, I don't need to make awareness grammar everywhere when I write and speak. I am FAMILIAR with some of grammar.
Do you still worry about your grammar ability a lot?
If a teacher tells you not to focus on grammar, get a different teacher. I would never pay money to learn from someone who can't explain grammar, or thinks that grammar isn't important. If you don't understand the basic grammar rules, you won't be able to improve your English.
If you say something that's incorrect, a teacher should be able to correct you right away. That's why you're paying money to talk to them. If you just want to talk to someone who speaks English, you can just get a language exchange partner.
I don't think it is so much a case of having forgotten the grammar as it is of thinking in English. It is true that as you reach the higher levels of language proficiency you will need to focus more on "polishing " your language skill, but you still need to pay attention to grammar. For example, even now in your post there are still quite a few grammar mistakes and it is written content. When speaking you have even less time to consider things like sentence construction etc.
