We are used to subconsciously "translating" what is actually meant from the exact words used, in part because so many people speak English as a second language (that they aren't particularly fluent in), in part because English is such an irregular language in places due to its historical development so even native speakers get a pile of things wrong, and in part because a lot of people particularly online deliberately get it wrong (building their own slang, references, and linguistic in-jokes that often eventually leak out into the wider awareness), and of course also in part because people who do know what is right sometimes make genuine mistakes.

The trick in any language is not to be perfect: it is about getting your message across and understanding other people's communication. If your English is good enough that I can understand your meaning without any great effort on my part, and you can understand what I'm trying to say, then your English is good enough (in fact possibly better, at least formally speaking, than some people native to the language!). Of course you should always strive to improve your skills, but try not to stress over it too much.