Not emptying breast/getting hind milk?

My baby girl will be 10 weeks old tomorrow. We are EBF but lately the side the nurses on still feels full/hard after she feeds especially in the mornings after her long stretch of sleep despite her nursing at least 20-30 minutes and sometimes longer. I use a haaka on the other side and it is always much softer than the side she nursed on. I do have somewhat of an oversupply and usually can fill up the haaka those first couple of feedings in the mornings and have around 550oz of a freezer stash for when I go back to work. But I am worried that she isn’t getting enough hindmilk. She weighed 5lbs 11oz at birth and weighed 9lbs 1 oz at her 2 month appointment and the ped was happy with her weight gain but I just feel like it could be better. She will feed for as long as I let her stay on there but she starts to fall asleep and use me as a pacifier but then again I hate to stop her just because I want her to get that fatty milk. Anyone been through this? I thought they get more efficient at BF’ing as they get older and feedings should shorten?