Here are my thoughts, having pumped as my only means of giving my son breast milk for 10.5 months now -
1) If you can afford to, buy a lot of pumping stuff, so you don't have to wash as often. Most of it can be done in the dishwasher. Early on my husband was washing it all by hand and that takes forever. Now, we wash the shields and bottles in the dishwasher. We have two little cages that they sell at Target that we put the little yellow things that go onto the shields, the bottle lids, the rings, and the nipples into. And then we wash the white pieces in the sterilizing bags. Doing it that way is a lot easier.
2) It is very hard to find time to pump when you are alone with him. I always made sure I pumped when I woke up over night b/c with my baby I could wake up, feed him, and then put him back down, he'd go to sleep and I could pump. If your baby is a pretty good sleeper at night, you could probably do that too. The best way for me to get as many pumpings in as possible was to pump as many times as possible overnight, since it's so hard during the day when he is awake. Now that he's older and on a schedule, on the weekends (during the week I pumped at work), until recently I would try to get up at 7:45, pump, get him up at 8, then pump towards the end of his morning nap (11:30), then pump during his afternoon nap (4:00), then pump after he went to bed (he goes down at 8:30). Doing that I got much, much less milk than early on, when I pumped 6-7 times a day. If you pump 3-5 times a day, my guess is that you will not get nearly enough. But, you can supplement with formula (which is what I've done for the last several months, once I went to 4 times a day), and know that he's still getting a lot of the benefit of breastmilk.
3) Early on, I probably pumped around 11 pm, then around 3 am, then around 6 am, then as much as possible during the day - but usually probably 3 times. If he gets to the point where he takes a good nap during the day you can do more. I would just do it as often as you can and if somedays you can't get as many, so be it.
4) My baby was always super hungry. I think by the time my baby was the age of yours he ate more than that at a sitting. He did not eat 8 times a day, I don't think - I think it was just 7. But I know I had calculated that he had around 40 oz a day. So, I don't know if the nurses are right or not, but my baby just liked to eat that much. He's very big - 31 inches and 26 pounds at 9 months - so maybe that's why. But I was never willing to sit and listen to him scream in misery just because the experts say that the average baby drinks 19-30 oz or whatever it is. I say if he's hungry, feed him.
5) I generally pump 15 minutes, but also have always gone ahead and kept on pumping if there was still a lot of milk remaining.
Hope some of that's helpful! Good luck, and remember that if you can't get enough milk, you can always supplement with formula. Any breast milk you give him is probably helpful!