I think consistency at this age is a bit optimistic really, she is still so tiny and doing so much growing. All you can do is keep things regular and it will get better. If she can go 3 hours in the day she *should* be able to go 3 hours at night, but it means you will be up more getting her back to sleep and then up soon again for a feed and if she is taking a full feeding she probably is genuinely hungry.
Does she have a dummy/ paci?
Laura