My first reaction is to think that you live a sheltered life if it has even occurred to you that the behavior you describe could even remotely be considered bad mothering.
My daughter is now 8 and I routinely say, in response to her requests for help, "I'll be there when I get to the end of this row." She has learned to accept it.
A friend of mine says, "Families work best when everyone's cup is full." So take your knitting in to potty training sessions and keep your cup full when you can. You'll both be happier, I think.
"One can never have enough socks."
A. Dumbledore, Book One, Chapter 12