Mom thinks I should work full time

I work 5 days a week at a public school (summers too) . I want to ask if I can reduce my work schedule to 3 days a week as I have a 4 month old baby. My husband works 2 overnights a week and is gone 48 hours so I’m all alone. We are financially able to do so and my husband is on board but my mom- not at all.

My mom and i literally get into fights about it. She watches our daughter 5 days a week but I’m not sure why she doesn’t want me to go part time. She thinks I have an amazing job but guys- I’m a secretary.........not a teacher or anything high up.

What do you think?