Hang in there, you can work through this.
Barb has given you some great advice - getting the best possible pump will help. You can contact your local ABA group to hire one for a couple of weeks. If you're a member it's very affordable. Otherwise, your hospital may be able to lend you one.

Definitely try waking to feed at least every 3 hours - it won't be forever, just till she's back on track. At each feed, you can switch sides after 20 minutes or so, as Barb has suggested, and even go back to the first side again if she's still interested after the second side. Doing breast compressions during the feed may also help to keep the milk flowing and your baby feeding, while also maximising the amount of milk that she takes. If you express between feeds you can give her that as a top up, but you can also give her top ups at the breast 20-30 minutes after a feed. (Sometimes this may be easier to do than expressing)

At this point, some formula may help her to get breastfeeding going again - it's not the end of breastfeeding.

Do you have much help and support at home right now? It is important to get rest yourself. If you can, try to let other things go for a time and maybe plan to spend some quality time in bed with your baby.

Take care and all the best.