Pumping help!

So my daughter is a month old now and has no trouble nursing and I know shes getting milk because she’s growing better than we or the doctors could have ever expected. I only have 4 more weeks till I have to go back to work so Im trying to build up a stash for dad when I go back. But every time I try to pump I can only get an ounce if even. I use to get more hand expressing but I dont have time for that. I know how to use my Medela pump just fine, I know how it works, I produce more than enough milk and eat lactation cookies but does any moms have any advice for getting more when I pump??