It can't be helped, maybe our educational system is to blame for English illitracy in Iran. Roghly speaking, barely on out of ten here can speak English. Speaking of Grammar, you know, when a soldier joins the army, they oblige him to carry his gun everywhere he goes, even toilet. They do it so that the gun becomes part of the soldier’s body which guarantees his optimum performance if the occasion ever arises. The same is true of grammar. you have to maintan grammar rules in your mind and consider them when you speak or write. If you do so, it becomes part of your natural speaking and you will observe them all subconsciously. As for how our English sounds to the native, just remind yourself of how Afghans way of speaking sound to you. It's odd yet understandable.