Of course, directly df is the best way to keep the milk supply.
if your schedule not suit to do so, you can try to be a full pump mama, but you must understand and expected to "pay more hard" for keeping the good milk supply, cant be lazy.
May be you need to pump mid night even your bb did not drink the night milk.
But you do can do if you really want to do.
I also be a full pump mama nearly 18 months without directly bf, if you have any query, please voice out, many mama can advise you solution.
Add oil, only you can give the best food to your lovely baby.