Re: how can I build up milk suppy before starting back to work
You can pump after nursing and probably will still get a small amount. That works for a lot of moms, they just combine those small amounts over time. Or if baby only nurses on one side you can pump the other side while he nurses. If you do pump and baby unexpectedly wakes up or wants to nurse soon after don't worry- you'll still have milk, since your breast is never actually empty and the pump will never be able to empty it as well as your baby can. It might flow a little slower, but your baby will not go hungry if he nurses after you've pumped.
Don't overdo it on the pumping beforehand, though. It sounds like you have an abundant supply and you don't want to end up with oversupply problems from pumping too much.
“We are not put on earth for ourselves, but are placed here for each other. If you are there always for others, then in time of need, someone will be there for you.”