I always used the 3 hourly rule (ie: feed every 3 hours when they are so tiny) so this equates to 8 feeds a day. If you are averaging that many a day I would say you are right where you need to be, she may be extending a bit longer over night (4-5 hourly) but I'm sure she is making up for it during the day by feeding much more frequently.

So long as she is having wet and dirty nappies and is alert when awake you are doing a good job.