Growth spurt or?

DD is 3 weeks 3 days old and i'm EBF. My breasts used to be really full right before i fed DD when she was feeding every 3 1/2 - 4 hours but now she has started to feed every 2 1/2 - 3 hours and my breasts dont feel full at all and DD has become really fussy. Sonetimes she will feed every hour for about 3 hours then go back to her every 3 houf feed routine. Is this a growth spurt or is my milk drying up and she isnt getting enough? Im really worried its the latter because as soon as i finish feeding, she will fall asleep, i will offer her the breast again and she wont take it and an hour later she will wake up crying for more food.
If anyone knows whats happening or if im just worrying about nothing please tell me  

Growth spurt this is normal and happening at the normal time. Expect it about every 3 weeks

Your breasts won't necessarily feel full after the first few weeks because your milk supply is regulating itself...Mine don't feel full anymore unless I go several hours without nursing (I alternate sides) but DD is definitely getting enough.

It's probably a growth spurt. As long as she's making enough wet/poopy diapers, don't worry about it.

Its a growth spurt.

Thank you!
Im a new mummy and just worrying about this that and the other ha ha!