Hypothesizing

Hi,

I know that for the hypothetical sentences the tense change is one tense forward

for non-fact to fact like the following ones:

would >>> won't
spoke>>>> don't speak
could>>> can't
had helped>>> didn't help

and vise-versa for fact to non-fact. But it seems that this rule sometimes

doesn't work.Look at the following instances and tell me what's the relevence

 between facts behind wishes and regrets and the rule mentioned above:

1-I souldn't have been speeding. (Fact>> I was speeding)
2-I should have listened to your advice. (Fact>> I didn't listen to your advice)
3- I'd just sleep forever. (Fact>> she can't get any sleep because of the kids)
4- Which one would you choose if you had the money? (Fact>> They don't have

 the money)
5- If I didn't get so nervous, I'd get better results. (Fact>> I get so nervous, I 

don't get better results)
6- If you'd helped us, we'd have finished by now. (Fact>> you didn't help, we

 haven't finished)

And is it correct to conclude that it's the if clause which conveys the wish and the fact 

behind it?(like sentence #4)

Regards,

Iman