Is it permissible for me to perform ṭawāf for ‘Umrah with my mother despite being on my menstrual period, and will this ‘Umrah be counted?

It is not permissible for a menstruating woman to enter or remain in the mosque, due to what was narrated from the Prophet, peace and blessings be upon him: "Indeed, I do not permit it for a menstruating woman nor for one who is in a state of major ritual impurity (junub)." The statement of Aisha to the Prophet, peace and blessings be upon him, "I am menstruating," and his affirmation of her, indicate that a menstruating woman does not enter the mosque. As for your mother, it is possible to hire someone to perform the rituals of Umrah (definition) on her behalf. As for you, wait until you become pure, then perform your Umrah. If you fear not attaining purity before the end of your visit, then stipulate at the time of assuming ihram (definition): "My place of release is where You detain me." If you are unable to perform Umrah after that, then you may exit the state of ihram, and there is nothing upon you.