Breastfeeding & returning to work: building a milk stash?

I have 4 weeks of maternity leave left and I was going to use this last month to start pumping as much as I can/as much as I feel comfortable, to freeze milk and create a stash to give to my mom when I go back to work because my mom will be babysitting for me.

I’m reading now that breastmilk can lose a lot of nutrients/vitamins when it’s frozen especially over a longer period of time.

My daughter will be almost 3 months when I go back to work and I’m hoping to breastfeed till at least 6 months when we can start introducing some solids. Not sure if we’ll switch to formula then.

I was so sure I was gonna build up this really great stash for my mom to have when watching my daughter during the day but now I’m wondering if it’s even worth it? I guess one perk is saving money on formula for a little longer. Whats a better way to make sure my baby has enough milk during the day?? My shifts are only 8 hrs but still I like to be prepared and have extra in case of growth spurts or hot days when baby wants to drink more.

Anybody wanna share their experiences and stories? I’m looking for different options. Thanks!