Exclusive pumping

Hi everyone. I have a 2 month old baby boy who is drinking only breast milk that I pump. I spoke to a lactation consultant and she told me to give him 2.5-3oz of breast milk every 3 hours. I was giving him 2.5 and he still seemed hungry at the end of his bottle. (We pace feed). Now he upped him to 3 ounces every three hours, and he seems to be doing better, but I am just making enough milk to feed him. I'm not sure what to do in terms of feeding him. I want him to be on only breast milk, but I'm scared of never having a stash and pretty much having to worry about making enough milk at each pump. Any suggestions?