I dont know if this is the case, but here are some things that I suspect:
1. Growth Spurt. How many weeks is he? You said for 2 weeks it went well, then it got rough. Thats a classic time for a growth spurt (2 - 3 week time frame). Then the next big one is at 6 weeks. Is he around that mark? (Give or take a week). You were going through a tough time getting him off of supplementing, which explains that part, but now that youre done with supplementing & "back at square one" it just sounds a lot like a growht spurt.
2. Expectations - I hate this one lol. Breastfed babies simply do eat more often. Youve supplemented, so you may have had a little bit of a break in terms of how often youre feeding baby. For the first 6 weeks, its totally normal for them to eat every 1 - 2 hours. Then it will start spacing out a bit more, 2 - 3 hours. Breastmilk is digested MUCH quicker - in as little as 20 mins. So literally - in an hour - theyve had an empty stomach for 40 mins! And that space of feeding time of 1 - 2 hours is from the BEGINNIGN of hte last feeding, not from when they finished... which many moms dont realize. So just a heads up onthat one
3. Pumping - you are actually pumping a GREAT amount for having a newborn. if youre able to pump 1 - 1 1/2 ounces (both sides combined) thats actually really good. It goes back to expectations. Moms see those 6 oz bottles and think they should at least fill them halfway, but so not true.
Heres a good link on it:
http://www.kellymom.com/bf/pumping/milkcalc.html
At one month, an infants MAXIMUM stomach capacity is only about 2.5 ozs!!! And thats not necessarily how much they eat a ttime either!
At one time - if you are feeding expressed milk, feeding every 2 hours, they will only be getting about 2 ozs on average each time. If youre pumping 1.5 ozs, thats GREAT!!! Your baby is more efficient than the pump, and you get a good bit just from the let down itself... so keep those things in mind!
Add just 3 more feedings a day in (eating just a little more than an average of every 2 hours) and thats only 1.5 oz per feeding!
So hang in there... I would say spend another couple days in case this is a growht purt just nursing, yes its tough but its so worth it.

YOu can make it through - it will liekly only last 2 - 3 days if you stay away from supplementing (supplementing drags it out). Count wet diapers and thats how you know hes gettin genough. With growht spurts, theyre getting enough at a time, just need more to signal your body to increase the calories & amount as they grow & their needs grow
Lala...