Supplementing

Is anyone supplementing with formula because they can't keep up with the demand of BFing? I've only been getting out 4oz from both breasts per pumping session which is not enough for me to build up enough of a stash to be able to leave my house and have enough for baby if someone is watching her. It has started affecting my mental health because I really didn't want to give her formula, but I literally never leave my home because of this and it's pretty upsetting.