Boobs don't feel full

Chantel
Hi, I am currently trying to breastfeed my 11 day old daughter but I'm not sure if she is getting all the milk she is meant to be, when she was a couple of days old she was sucking good but now she seems to have just gotten lazy and it feels like she isn't even sucking much anymore and there is no pain at all, I ended up getting a nipple guard thing and I can see that it fills up with milk so she is getting some but inbetween and before feeds it feels like my boobs have been so soft and it feels like they arnt filling up and getting hard like they did, I have a machine to express milk and I am getting some milk (about a normal feed) in the bottle but not as much as when I first started doing it, Has anyone got any ideas why this could be ? She seems to drink and suck from the bottles better but the nurses have said she is attaching to my boob properly so I'm confused :(
Thanks and hopefully someone has some suggestions x