Ladies, I am struggling!

I have been worthless all week at work so far. Luckily it's our slow time and my boss is out on vacation, but I can't keep this up long term! I am seriously struggling all day long to keep my eyes open. Coffee isn't cutting it .... I'm up to 4 cups a day.

LO is three months old and his night sleep is pretty good, just not consistent yet. We try to start his bath/bedtime routine at about 8 pm every night and I nurse him to sleep. I try to go to bed shortly after he does to get as much sleep as possible, but I also need to clean the apartment, spend time with DH and do other things in the evening! LO usually sleeps in two chunks - the first anywhere from 3-5 hours and then a second shorter chunk usually 3-4 hours. A few times he has slept for 7 hours, but I wake up in pain and engorged about 5.5 hours in. I breastfeed, so no help with nighttime wakings.

Any tips or advice?? I've never been so tired and it's affecting a lot of my day to day life.

ETA: I'm usually out of bed by 5:30 AM (sometimes earlier) to get ready for work each day which includes eating breakfast, makeup, getting dressed, packing a lunch, etc. I also pump in the AM and I'm afraid to drop that pumping session since I can only pump twice at work.