Hey I'm 6 weeks and I think there were times I went over 4 hours. Right now I went over 5 hours twice in the last two nights!! I'm kind of worried. I can tell you though my output is trypically 4oz on avergae but can be in the 3oz-6oz range depending on time of day etc. I have a bit of a struggle getting enough imo so IF your doing better than me at 3 weeks I'm sure you'll be fine. It happens just don't go over 4-4.5 like I have done! And I typically make it up so I'm getting 7-8 pumps in a day I try and go for more to make it up if I can. Good luck!!
I'm about 3.5 weeks pp.