No more milk...

My baby will be 4 months old tmw. After I went back to work 2 months ago my supply took a hard hit. And for for the past month ive only been able to BF in the mornings and at night and pump once during the day. Now I can’t get more than 2 ounces at a pump session and don’t have enough milk in the evenings and mornings any more to satisfy my baby. Last night and this morning I ended up having to feed supplement after about 5-10 min of nursing. I feel like this is the end of breastfeeding for us. I’m thinking that once we finish up this tub of supplement formula (if I have enough supply to make it that long) we are going to switch to formula. Any other advice?