I had thought that you also taught English, although i do not now remember why i had come to that conclusion.
Your English is excellent. Many, many years ago, while employed in the Department of French at a midwestern university, i also volunteered to teach English as a second language. At that time in 1980, an event took place which is known as the Mariel boatlift--
you can read about the Mariel boatlift by clicking here. So many Cubans arrived in the United States unable to speak English, that the government sent those whom it had cleared for resident status to universities all over the country to learn English, and volunteers were pressed into service all over the United States. I had already encountered a book entitled
English Grammar for Students of French, which had taught me more about English grammar than i had learned in my entire previous life, and it stood me in good stead in that time of need. Unfortunately, one usually learns one's language, and can learn to speak it well, without actually learning the formal rules of the language. That was more than 25 years ago, so i've probably forgotten more than i learned--but teaching English as a second language still taught me a great deal about my own language.
As i said, your English is excellent, and i applaud your efforts to improve. I would suggest to you that you now have a better command of the English language than many, perhaps than most, native speakers of English.