(1) Like you, I am also a native speaker who needs "further clarification" about many things, so I really enjoy reading the posts from outstanding teachers such as Fivejedjon.
Actually, I do take an arrogant pride in my understanding of some of the finer points of grammar [with the notable exception of 'labelling'] but, probably as a result of this, I think that I am a pretty lousy teacher. That's not false modesty - I think that my obsession with grammar has burdened my students with too much concern with grammar. The job of English teachers, I feel, should be to enable students to communicate in English, not to have a good theoretical knowledge of the grammar.
(2) I just wanted to add two comments:
(a) I think that many of us native speakers say something like:
If I
would have had time, I
would have come to your party.
(i) My teachers told me that it is
incorrect. It should be:
If
I had had time, I
would have come to your party.
Ths is a good example of what I was talking about above. 'If I would have come' makes me cringe -
but it's perfectly acceptable to most of the Americans I have met. So, in speech at least, it must be acceptable in AmE, regardless of my personal feelings.
(a) Some native speakers feel that saying "
had had" sounds "funny," so they (correctly) use a contraction: If I'
d had time, I
would have come to your party. (Now everyone is happy: teachers are happy because we used "had had," and we are happy because we did not have to say "had had.")