Would I be sinful if I went for Umrah, which I won, without my mother, knowing that she has enough money for Hajj, and I do not have enough money for Umrah?

It is not a condition for one who is able to perform Hajj that his parents must have performed it before him, nor is the consent and permission of the parents a condition for performing the obligatory Hajj. However, one must be gentle with the mother and persuade her. As for a voluntary 'Umrah, it is not permissible to travel for it except with the permission of the parents. It is not permissible for parents to prevent their child from performing the obligatory Hajj and vows, nor is it permissible for the child to obey them in abandoning an obligation. This also applies to an obligatory 'Umrah.