That does seem a little slow - but could easily be the difference in being weighed pre- and post- pooh, for example. The most important things are lots of wet nappies and that when she is awake she is active and alert.
It is worth offering the other side - more than anything she might start letting you get more sleep if she has more in her tummy. But don't push it - she'll either take it or she won't. And the attached for an hour also indicates that she is doing her job of putting in her order for more milk when she needs it - which is a good thing.
Weigh her again in a few weeks to check, but I don't think you need to worry.