I found recently that all women should have a wali or Wakil(layer) to represent them during the Nikah otherwise the it is not valid.

This is my second marriage.

Before the marriage, I told him I need someone to represent me because I have no male relative, the Imam who did our Nikah had told me I don't need one and I can represent myself because I was a divorcee and two of his relatives witnessed the Nikah and that's enough.

We have a child together now.

I have the following questions:

Was the Nikah valid? Have I committed a sin because I didn't know? What can I do or how can I repent? What will make of our child if the Nikah was not valid?

I'm scare, afraid I committed a sin unintentionally. Any guidance would be gladly appreciated.