There are so many things going on here that it is difficult to respond. I am an experienced mother and have nursed all three of my children (now ages 14, 9 and 2). I was back at work after three months with my first and lucky enough to stay home with my two boys. I found la leche league REALLY helpful in supporting my breastfeeding efforts. They are all nursing moms who believe that breastfeeding is best, as much as you possibly can! AND they have decades of experience to offer. In lieu of contacting your local La Leche League leader, I'll share some of what I've learned.
1. Every child is different, they all have their own needs and wants and even nursing styles
2. As time progresses, your milk changes. As a child ages, our miraculous bodies know EXACTLY what to produce for our children
3. Stress makes being away from your little one and pumping less and less successful. Relax and trust that you are doing the right thing...
4. Hydrate, hydrate, hydrate, eat nutritiously...just as if you were with your little one full time, this will make pumping much easier and more successful
5. Your baby knows a lot more than you think she does, if she wants to nurse, she needs to nurse. Little ones require the closeness of human contact to develop properly both physically and emotionally. If you are adding solids early...don't forget to do extra cuddling! AND, don't forget that your body is producing EXACTLY what her nutritional needs are.
6. Again, infants, especially in the first 6 months...NEED human contact and the satisfaction of sucking...it is important for everything...
7. YOU CAN DO THIS! If you are determined that breast feeding is best, then, work to adjust your routines when you are with her to make that happen...she LOVES YOU and NEEDS YOU...so, if you are a working mom, expect to spend a lot of time when you are with your little one, breast feeding. Maybe even more often at night...it's not just about the nutrition, it's about human skin-to-skin contact, it helps her brain develop, it meets her emotional needs...yes, emotional...that's important for a healthy baby too!
8. MOST OF ALL, TRUST YOUR INSTINCTS! Appreciate this time, it will pass quickly (as you already know since you have an older child). She won't be this small or need you this much forever, allow some other, less important things, to go and spend as much of your non-working time with your little one as possible..before you know it you'll be potty training!
Hope this was helpful. Good luck in your efforts, you'll have a healthy baby and it will all work out!