I am a bit confused with the ANA rule in the Quran.

Question
Salaam,
I am a bit confused with the ANA rule in the Quran. I believe that all ANA’S should made short even though there is an Alif next to the letter Noon. I also believe there are exceptions such as ANA SIYYA, ANA MILA which the Noon is made long. It would be grateful if you can advise me on the rest of the ANA’S in the Quran that can be made long.
JazakAllah

Answer
Wa alaikum assalaam wa rahmatullahi wa barakatuh
The rule for the word is only for this word by itself meaning "I", and not for anytime the combination of letters occur in other words. 
You will notice the symbol over the alif.  This symbol indicates the alif is pronounced when stopping, but dropped when continuing. 
In the other words listed in the question, the words contain the combination of hamzah with a fathah, a , then an alif without any symbol over it, but they are part of words and do not mean "I", instead are part of the make up of another word, so the alif is pronounced with a two count lengthening, that of a natural medd. 
Wa iyyaakum
Wa assalaam