I hope you can see your oncologist as soon as possible to get all the answers you need. Most likely it is stage 3.
N1: 1 to 3 regional lymph nodes involvement.
Mx: The status of distant metastasis is unknown or cannot be assessed.

I believe there will be some updates on Mx.

My father's diagnosis is T3d N2 MRF+ , stage 3 rectal cancer.