Am I making less milk??

(Baby is 4 weeks old today) All of a sudden my baby needs both breasts to be satisfied. She used to just take one breast, suck until she was hally and then that was it, the other breast waited until next time. Now though, seemingly all of a sudden, she will keep sucking and sucking until she gets frustrated on the first breast and I can tell it's pretty much empty (very slow flow making her mad) so I switch her to the other side and she drains that side right to empty as well.

Also, my breasts arent getting as full as they usually do, between feeds they used to get really big and tight feeling and spray everywhere because the let down was so forceful it was like a water gun. Now, if they get the chance to leak, it's just drip drip drip, and they never feel full or anything just slightly harder than when they're drained and then shes hungry again.

So does it sound like my supply is dropping or is my baby maybe having a growth spurt and my breasts arent filling up because shes drained both when she used to only do one...?