Hi again haz -- I guess you're not in the UK, posting at 4 in the morning, or are you just insomniac?
Agree with gothicmama that ignoring m-i-l is absolutely paramount. (((Hugs))) and sympathy -- my m-i-l does this kind of thing, too, and it's the last thing you need. Maybe she bottlefed her own babies, in which case she may feel threatened by your bfeeding success. If she bfed successfully, presumably she's not offering to whop them out right now and feed the baby for you, so she doesn't need to have an opinion on it except to tell you how brilliantly you're doing and what a wonderful mother you are. If this is your first baby, then bfeeding is only the first of hundreds of things she's going be criticising you for, so you may as well fit your ears with bypass filters right now.
Also, the amount you can express isn't really an indication of how much your baby's getting I'm rubbish at expressing, but in the early days even I could express a bottle-full cos the baby's feeding patterns are more irregular, so it's more likely there'll be a surplus at odd times. Now the feeding patterns are (presumably) a bit more settled, there's less extra building up waiting to be expressed hence less full and uncomfortable boobs, too.
Sounds like your dd gained loads early on, and has now slowed down, which as tiktok says, makes perfect sense. It is very hard in the early days when you feel insecure about it all, but it sounds as if you're doing brilliantly and your baby is fine and healthy. Maybe you should tell your lovely paed how your m-i-l is giving you a hard time -- I'm sure he will have heard similar stories before and should be able to reassure you. In the meantime perhaps you should develop a mysterious malady that means you need total rest and no visitors at all...
Keep us posted, and take no nonsense.