I understand your answer and appreciate your examples. However my concern is the fact that NOU ends in a vowel. Shouldn't it be nou A. For example in one of the examples you mentioned, there's SE N NAN, so the article NAN is there because of the N sound that we now here even though we know it's a contraction. So since NOU ends in a vowel sound, why is the article not A?

Hi,

That's because the "OU" sounds is also considered a nasal sound.  You will find a small percentage of people who will have a non nasal vowel after the "ou" sound, but we mostly have a nasal vowel after an "ou" sound.  Some examples:

Bondye nou an (our God)
lanmou an (the love)
jenou an (the knee)
bagay mwen te ba ou an (the thing that I gave you)

FYI:
Sometimes an definite article that would otherwise be non nasal, will be written as a nasal vowel if the first syllables of the word have a nasal sound.

For example
"Zanmi" ends with "I"
You will be tempted to say "zanmi a".
but because of the first syllable "zan..." which has a nasal sound, we would sometimes say "zanmi an".

other examples are:
fanmi an (the family)
lanbi an (the conch)
konduit lan or conduit lan (the behavior)
konsè a or konsè an (the concert)
Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words