Breasts feel so empty!

My little one will be 3 weeks tomorrow and today my breasts suddenly feel so empty. Like literally deflated and it's weirding me out, they're smaller than before I got pregnant. Is this normal? Also having issues pumping, I can't get the suction I used to because they're so flat and not full anymore. Is this anything to be concerned about? She seems hungrier too which I suppose could just be a growth spurt? Just for reference I feed her mainly right from the breast but also pump a few times a day. I used to pump more due to issues with her latching properly but have since decreased the amount I pump now that she's doing well at the breast, not sure if that's what is causing this to happen. TIA!