Hey I just wanted to pop on here and give you some encouragement.
First of all, I TOTALLY get where you're coming from, even the excitedness (is that a word? LOL) over the breastmilk amount. I have a picture from my LO's NICU days where I'm giving the camera a HUGE smile and thumbs up while holding my 7 MLs of colostrum, LOL. You're doing awesome!!
Secondly, you are not a bad mom for not being there 24/7!! We were able to room-in just off the NICU (we lived 6 hours away, though) and even then we weren't there all the time.....it gets really overwhelming and stifling to be in that environment for too long. I know that's not really your case, but seriously, just the fact that you WANT to be there means you're an awesome mom! I know of a baby who was left in my hometown NICU and her parents lived a province away (I'm in Canada) but they couldn't (/wouldn't?) make the trip to where she was until she was ready to go home, which could have taken 3 months, she was really premature. I saw her on my hospital tour for my prenatal classes and I bawled my eyes out when I got home! But as much as I wanted to be angry at her parents, I'm sure there were reasons (probably monetary) that meant that they couldn't be there. There are parents all over the place that just leave their babies in the NICU (yes, I'm serious).
I can totally relate to how you're feeling right now, it's so hard to feel like their mother when you're not there all the time or attending to all of their needs. My LO was hooked up to....a shit-ton of tackle (we're talking respirator, oxygen, cathetor, 3 IVs....etc.) and it was heartbreaking that when we got to "hold him", it was basically them (and I say "them" because we needed a nurse and a RT) placing him on a nursing pillow on my lap. I couldn't move him at all, no skin-to-skin, and I had to stay like that for at least an hour. That was so hard.
BUT on a positive note, the fact that your doctors are "up beat and positive" is a HUGE sign of awesome. It's when they aren't up beat and positive that you have to be worried. (Yep, that happened to us too. But even when they delivered bad news, I gotta say, they were very very good about it).
Anyway, hold on there mama, I promise that this NICU stay will just be a blip in his life, even though it feels like years now. If you ever want to vent, talk, whatever, feel free to email me: firstname.lastname@example.org
Take care! <3