To Have Or To Have Not or Too Typical The Dilemma

I should have

I could have

I might have

I would have

I might not have

I wouldn't have

I couldn't have

I ought not have

If I hadn't

If I had

I should have

If only I did

If only I had

If I didn't

If I did

I could have            and on and on and on, or perhaps it really doesn't matter after all, does it?