I can't tell you anything about bottle feeding, mine has always been breast fed. But i can tell you that babies usually still wake up at that time for a feed. My daughter was 8 weeks old when she stopped that, but she was still have the 10pm feed and the 6am feed. now she sleeps from 8pm to 8am, but she is 5 months old now. It's great you are giving him water, in this heat (I'm from north qld) they need water. Bottle fed babies are naturally bigger then breast fed babies, because of the formula, it can't be fully matched to breast milk, but he will grow out of it. I know lots of large babies on the bottle and they grow out of it by the time they're 2 years old. I wouldn't be holding back on the feeds otherwise he will be unsettles. He knows what he needs, and if he needs a feed he won't be happy until he is fed, then he will settle.
You sound like you're doing a good job, keep it up.
mother to Hannah born August 9 2003