I know I'm a good mum. We've had more than our share of troubles. DH died when my sons were still at primary school and both of them have had significant long term health problems.
But they're young adults now and I know they think I'm an amazing mum, as does my DSD, who's now married with DC herself. My deep attachment to her goes back 32 years.
But as others have said, I'm an amazing mum because I had amazing DPs myself who demonstrated excellent role models and have supported us in every way possible.
I once met a woman who had three small DC from three abusive relationships. She was a care leaver who told me about her DM, who beat her with coat hangers and locked her in cupboards.
She said her social worker tried to help but that being a good mum (which she so desperately wanted) was hard when you've never witnessed it.
I told her what a social worker I know once said: that if you ask yourself whether you're a good enough parent you are. Bad parents never even think to ask themselves the question. I also recommended books I'd found useful. I praised her and hope she felt supported by what I said.
But it really brought home to me how very lucky I am to have been born into a loving functional family which gave me the tools to be a good parent.