Your dd sounds pretty normal. My lo slept a lot when I was feeding him when he was that young. I don't think the sleeping is necessarily related to your supply. If you are concerned, don't worry about EASY and just feed on demand to ensure your supply is up.
Remember, the extra time you spend nursing right now you save later on, in the way that you don't have to prep bottles, etc.
Good for you for sticking with it... it must be really hard with another lo to look after.
All the best.