Maybe its her personal experience as a motherless child that is making her want to be ready to look after her own child and give it all that she has missed out on. And as part of this readiness she wants to be emotionally ready to take on this responsibility.
Nidhi knows what exactly she has missed by not having a mother.Nidhi was a little girl without a mother's love that so many of us just take for granted. Mother's value as a role model and friend is undeniable. There is no substitute to mother in our life. No one can take that place. In Nidhi's case Shyama aunty and dadi bua can not make up for her loss.
So she wants to be a perfect Mom and give all the love and care that she missed out. i appreciate her decision to wait till mentally prepared for motherhood.Her worrying itself indicates that she will be a good Mom