Hi! I went back at 6 weeks (actually earlier, but I was able to have him with me before 6 weeks) and pumped for his bottles. It's a lot of work but very much worth it. I was able to take 2-hourly pump breaks when I went back because he was obviously still going through the early growth spurts and I had to pump frequently to simulate the spurts. I was then able to gradually increase the time between pumping sessions/decrease the number of sessions per day. Honestly, I found the sticky at the top of the page about exclusively expressing to be hugely helpful (because depending on how many hours you work, it comes very close to exclusively expressing sometimes).
I was able to pump enough to feed DS1 and then to pump extra enough to donate through milk-sharing, so it's definitely possible to produce enough to feed LO while pumping at work.
The best things I ever did were:
1) schedule an early morning pump session-- you're going to be fullest in the morning and any milk you pump during the time with your baby is just going to be that much extra backup you'll have if you run into problems pumping while you're away from your baby. Sometimes I would get it in before he woke up, sometimes I would feed him off of one side and pump the other, because that will help him get more milk out of the side he's nursing and his nursing helped me get more out of the side I was pumping.
2) get a hands-free pumping bra (the arden bra is nice, but you don't necessarily need such an expensive one)-- shit happens sometimes. Sometimes I absolutely had to get something done on my computer during my pumping sessions, sometimes shit really hit the fan and I was pumping in the car on the way to work. Either way, there were times I absolutely needed to pump hands free.
3) Trust my body-- there is always milk in your breasts. It doesn't matter how much you just pumped, how empty they feel, how much your lo just nursed, there is always milk to be had unless you've developed a new medical condition (thyroid issues, another pregnancy). I hear so many women worrying about when to pump and how to build up a stash when their LOs are nursing frequently and they're scared to pump one side and feed the other because what if they don't have enough for LO during that session. You just do it-- there is milk. If LO is still hungry, you just put them to the breast again. If you need more milk than you're getting, you pump for 5 more minutes after it's stopped flowing. The only way to get more 'easy' milk is to demand more milk.
4) Make sure the problems are worked out in that first month. Don't wait for problems to see a lactation consultant-- dig the well before you're thirsty. Make sure there's a great latch and put LO to the breast as often as humanly possible in those early weeks-- set yourself up for a bulletproof supply by building and building those prolactin receptors.
5) Learn to hand express effectively-- one day you will forget the pump at home. There will also be days where you're not feeling well and the milk just won't flow as nicely. Many times once the pump isn't doing it anymore during a session, women can successfully hand express more milk through good technique and effective breast compressions. The lactation consultant can walk you through this as well.
