Pumping and Returning to Work

I am so anxious about feeding my little one when I return to work. breastfeeding is going great. She is 2 and 1/2 months. I feel like she is eating every 2 hours but we have been traveling. She also may be having a growth spurt so those may be contributing factors to that. I return to work in about a week and a half. I will have 12 4 oz bags of frozen milk. She does take a bottle. I am nervous that I won't be pumping enough. My little one is a big girl. I will have time to pump at work but it will be limited. I feel like that stress and pressure are going to get overwhelming and as a result pump less milk. Suggestions?