So he is 6wks going by your ticker. You will find your supply and demand has probably settled down to what he wants only. I wouldn't worry how much you can express.
Do your breasts feel full and can you feel a let down when he goes on? A let down can sometimes be felt not always, it's like a tingly feeling.
He could just be having one of those days as well.
Has your AF started back or have you started a mini pill? I found when DS2 was 7wks old, we had and absolute horrid 24hrs, it coincided with me taking the Mini Pill and AF returning.
We just had to ride it out. Alot of babies at 6wks just seemed to have this horrible 24-48hr period where nothing seems to help
Here is a lactation cookie recipe Kelly posted a while back,

https://www.bellybelly.com.au/forums...es-recipe.html

If you feel your supply has dropped, try baking these.

Also post here, she really is wonderful.

https://www.bellybelly.com.au/forums...lare-question/