Hi there...

I returned to work when Indah was almost 6mths old, I had about 2 litres of expressed breast milk in the freezer (in approx 220ml lot's each) I then gave my sister whom was looking after Indah 3 bottles worth (I would give Indah both breasts before work in the morning) then I would express 3times a day & get about 250ml each time & bag that up to be either frozen or given to my sister for the following day, I'd then feed Indah whenever & how ever often she wanted breast from the minute I walked in the door at night, sometimes she'd only have 2 bottles & on weekends I let her feed all day so as to make sure I had ample supply!
I fed her til she was 14mths & I would have kept feeding but I was pregnant again & she refused breast & went straight on to cows milk from a cup, so it is definately possible! Make sure you drink plenty of water & eat well so you make enough milk!