My name is ***** ***** I am a NSW Solicitor. Thank you for your question, and will do my best to assist you with your question. Please understand this is not legal advise but a guide to assist you.
This is not a legal term and is therefor given its everyday meaning
If you are to get orders the court orders that the child resides with a parent and the other parent spends time with the child.
Each parent has the care and control of the child whist the child is in their care.
If you were to say which parent spends most time with the child that is the parent that has residency.
In relation to parental responsibility i.e. making major decisions about schooling medical treatment etc you both have equal responsibility and noone has more than the other.
In your case you have almost shared residency of the child.
If you look at time the child is with each of you taking into account awake and asleep then the mother has more time by 2 days. But the courts would never decide on who is the primary carer as you are both responsible for the care of the child when the child is with you. You are both primary carers when the child is in your care.
The time then child is with each of you makes no difference about major decisions. You both have to be consulted.
I am not sure why you are asking the question but as I said the term is not a legal term and not used in any orders.