My sisters boy fed four hourly from day dot and went 8 hrs overnight as well. She didn't enforce this routine it's what he seemed to 'demand'. It worked for her and she fed him until 12 mnths when she weaned. My DS was different and was fed much more often. There are all kinds of normal and I also found once I had a routine DS would change

If she is gaining weight and has plenty of wet and dirty nappies everything is going well. As others have said breastfeeding works on a supply and demand basis so if you want to stop the comp feeding the best way is to bf more/longer. Often it only takes a few days of extra feeding to boost supply. Please know expressing is not a good indication of supply because the pump isn't as effecient as a bub's suck.

sounds like you are doing a great job