I'm so upset 😞

So after putting so much effort into breastfeeding I'm afraid it's going to have to come to an end & I am soooo torn up about it. I'm going back to work Friday & I have a little stash but only enough for a whole days worth of feedings since I have had problems pumping. My schedule was strictly night time so fiancé could be with LO but they decided to schedule me for training ALL day from 7:45 am - 5 pm so now fiancé has to take off work to stay with LO, & all my milk stash will be used up that day. I don't pump enough at a time to be able to keep pumping so LO has enough to eat while I'm at work. Plus these last couple days, it seems as if my supply has dropped drastically. So I guess I'm going to start mixing half & half breastmilk with formula until my little stash is gone then LO will strictly be on formula.. I'm so upset. But I don't really have any other options. Has anyone dealt with something similar? any advice on the switch?