I am an EPer and my baby is now drinking 6 oz of milk every 4 hours. I am barely making it, but she is almost 4 months old. I am kind of sad that I might have to get formula supplementing, but may be she will stay with 6 oz for a while. My goal is to make it to 6 months, but with full time work it is so hard. We might not be exclusive on breast milk anymore.

Babies grow up so fast!
Re: Can't keep up with the demand
I am pretty much the same. Don't get upset if you have to supplement with formula. I have such a limited supply, and I got so upset when I had to start feeding DD primarily forumla, but we do what we have to do for our LO's best interests. There are supplements you can take, as well as prescription meds to increase your supply as well.
Diagnosed with PCOS March '10 - Started 1000mg of Metformin

After 3 unsuccessful Clomid cycles, FSH+Ovidril+IUI+Progesterone=BFP!
Time to make Emilie a big sister!
May '16 2.0: Letrozole+FSH+Menopur+Ovidril+IUI+Progesterone=BFP! first beta-45.44, second beta-148
The best thing that helped me was getting on a pumping schedule. That did more for my supply than the fenugreek...
Also have you tried any lactation cookies? They're a good, fun way to try and boost supply :-)
I EBF for 8 wks, then finally decided to supplement. My son lost a lot of weight in the first few days (a full pound) and was not gaining it back fast enough. At almost 2 months, he was only back to about his birth weight. He was still peeing and pooping throughout the day, sleeping fine, etc. But at 7-8 wks (growth spurt maybe?) he started getting fussy, wanted to eat ALLL the time, and got fussy (more like screaming) at the breast- I assume because he wasn't getting enough. I started pumping but couldn't get much after a feeding at first. After a day or 2 of that, I couldn't stand the thought that he might be hungry. I cried through his first bottle of formula. I thought it meant I had failed at BF and failed as a mother (dumb, i know.)
Well, he got happier by the day and gained about a pound in a week! We're now about 50/50 and i'm still pumping all the time to get my supply up. I don't think I will go back to 100% EBF, but I won't stop either. We now nurse, then have a few ounces in a bottle then I pump. It's nice to have the convenience of formula too (I am not one to NIP) so we're now going out more and just enjoying our days more.
i'll stop blabbing... bottom line, listen to yourself and do what you think is right, but supplementing isn't a bad thing.