As a full-time working mom with 2 kids, I'm going to pass along the BEST advice I ever received with regard to getting organized with your newborn. Pick up the "On Becoming Babywise" book by Gary Ezzo, and implement it. Your newborn will sleep through the night, I promise you! With my second child, I had to move out of our house with my 2 year old and my newborn (our home was being remodeled) and had to move in with my parents, who live 2 hours away. So at night, I had no help at all. I did the Babywise thing, and I'm telling you now, my little one was sleeping through the night by 4 weeks old. It was like a miracle to me!
The basic idea is this. You have a schedule, which you can adjust as needed for growth spurts, etc. You need to feed the baby, then have awake time, then sleep time, and this feed-play-sleep schedule runs on a 4 hour cycle during the day. For instance, 6am feed the baby (BIG full meal, change the diaper halfway through to wake 'em up, burp, etc etc - pack that baby full of milk), then awake time (go for a walk, go to the grocery store, baby sits in bouncy seat while you fold laundry... whatever your routine is). Then at 9am, put baby down for the morning nap, awake but calm. DO NOT feed your baby to sleep. You need your baby to be able to fall asleep without your intervention. Baby falls asleep, sleeps until 10. Wakes up hungry. Repeat the cycle. Feed baby, have some awake time, at noon baby goes down for nap #2, sleeps until 2pm. Wakes up hungry. You feed baby, have some awake time. Bath time at 5, feed baby, cuddle before bedtime, and baby goes down to sleep, awake but calm, at 6pm. Yes, I realize that sounds like a crazy time to put a baby to bed, but trust me, it works. I don't know why, but when you put a baby down at 6, they will sleep for HOURS. A newborn might wake at 2am for a feeding, a 1-month old may sleep through the night completely. Start your day again at 6am.
And voila! That's the secret. I promise. When your baby knows what's coming next, he will be calm and happy. When your feedings are somewhat scheduled, your baby will eat big, full meals, which helps with your milk supply and helps your baby not feel hungry again so quickly. And, since your day is pretty much scheduled out, you know when you can plan to do things and not run into a feeding time. When you are calm and happy, your baby will be, too.
Once you get the sleep thing down, returning to work is not so bad because you will feel well-rested in the mornings.
Take heart. This will get better soon! Go get your Babywise book tomorrow, read it while you nurse (it's a short book, and easy to read even when you are sleep-deprived! LOL). Hang in there, mama! You can do it! :)