Nervous to go back to work...

Brooke • Mother of 3! C-section mama, uterine rupture, and uterine resection. Long difficult journey to be a mama. Blessed with two boys & a sweet baby girl. (07/10, 02/16, 08/17)
My little guy was born at 34 weeks via cesarean. I immediately started pumping for him while he was in the NICU & kept going. I mostly pump every 3-4 hours and get 3-6 oz. I am very nervous for when I head back to work. So far I've been pumping for 16 weeks straight! I plan to keep going. I have a small freezer stash, but I am wondering if my sessions at work will yeild enough milk for him. Any suggestions?