When my lo was smaller I had really bad sleep deprivation. OH works a lot and there was no family or friends that could help. I felt like I was in a dream a lot of the times. I was eating fine, taking vitamins, drinking water etc, but it was too much with her feeding all the time, especially when she was cluster feeding.It was literally every hour all day and night, no long sleeps.
One time I had to call OH home because I actually started hallucinating! I saw bugs crawling up the walls and dd had a snake tongue! Kinda funny now but it scared the crap out of me! OH came home and I took a nap and felt better, but after that I made sure to sleep WHENEVER lo was asleep. The house looked horrible, I wasn't cooking and I was only wearing pj's all day, but it was what I had to do to keep sane for me and dd.
It does get better! LO started getting into a schedule and sleeping for longer stretches of time, but what REALLY helped was when I could predict when she would fall asleep next so it didn't seem like an un-ending feeding session. I actually started to be able to have days and nights again instead of just sleep for an hour, feed, change, sleep for 30 minutes, feed, change, etc. Looking back at my schedule (I wrote everything down) I am amazed that I did it, but you will manage!