I have to respectfully disagree with Grandma T. I in no way think formula is poison. But, if a mom starts substituting formula this early in the game, her milk supply is going to tank and it won't be long before the baby is on all formula. Which is fine if mom wants to stop breastfeeding, but it sounds like she was looking for ways to continue nursing for the time being. A month old is normally not on any schedule. They eat and sleep when they feel like it. His nursing behavior is very typical for a newborn, especially for a 4 week old going through a growth spurt. Things will calm down. I do think it's really hard to go back to work so early after giving birth and try to establish breastfeeding. I put some links about growth spurts and normal newborn behavior.
http://www.kellymom.com/bf/normal/growth-spurt.html
http://www.kellymom.com/bf/normal/newborn-nursing.html
The kellymom website is a very respected wonderful resource for breastfeeding moms. Check out the forums with include a pumping forum with many knowledable ladies in the same boat.
Some things you could try come to mind...
-Make sure you're using slow flow nipples
-Learn how to pump handsfree so you can do things like eat and type on mamapedia while you pump. They sell handsfree pumping bras, but this is what I did: http://www.kellymom.com/bf/pumping/hands-free-pumping.html
-Nurse on one side and pump the other at the same time.
-Consider cosleeping or at least how to nurse side lying: http://www.babyzone.com/baby/feeding_nutrition/breastfeed...
-Maybe consider talking to the lactation consultant who helped you in the hospital? Usually they are a free resource if you've given birth there. They could also reevaluate your latch just to double check that he's nursing efficiently.
-Know that every time he nurses, he is stimulating you to increase your supply and make more milk. I remember very well how exhausting the constant nursing is since my first didn't take pacifiers OR bottles. It may seem overwhelming, but it takes about 3-4 months to get your supply established, so if breastfeeding is very important to you, remember that all the crazy nursing is there for a reason and it DOES get better. As far as using you as a pacifier, it's exhausting, but it's normal. It's why man-made pacifiers are nipple shaped. You're fulfilling your child's needs not spoiling him.
I think you're AMAZING for breastfeeding, pumping and working! It is not easy to do that and you have to be really dedicated. Working and nursing can be incredibly challenging although not impossible. I know a few people who ended up exclusively pumping and working and they made it work. Good luck!! (And congrats on your new baby.)