Ok, this is what is so hard with medical people. They like numbers. And how in the world are you supposed to measure that if breastfeeding? Seriously, I have NO IDEA how much my son is taking in quantity wise. My first question when I hear "hard" numbers is: "Are those numbers for formula fed or breastfed babies?". Because the numbers can definitely be different. Your milk is perfect for your baby's caloric needs.
THE BEST way to know if you baby is getting enough is by counting wet and poopy diapers. Period. What goes in must come out. Looking at the output will tell you something about the input.
I would look at this: http://www.llli.org/FAQ/enough.html
Honestly (and I don't mean to sound snarky), but since this is my second baby, I have not really looked at the clock, or counted diapers or anything like that. I am an engineer so with #1, I had spreadsheets of this stuff! But this time, I let him eat as much as he wants and as long as he wants, whenever he wants. It is so much easier to be zen about it when you have gone through it before and know it works out (my first had latch issues, I had to feed him formula for a month, and then get him back to the breast while recovering from a c-section/pneumonia/septasemia/early cardiac failure). Yep, I started losing my mind and I was so upset and freaking out. I did not want to fail at breastfeeding because I felt like I failed at birthing. And, it was seriously emotional and scary too. But, I stuck with it and DS1 still nurses at night before bed (he would nurse all day if I let him, but I can't handle nursing a toddler AND infant all day long :)
Stress WILL affect your milk supply. I would consider the Hypnobabies track on breastfeeding and play it while you are going to sleep (http://www.hypnobabies.com/store/shop.php?pid=47&sid=9&cid=9&start=0). I was much calmer about birth because of the pregnancy affirmations, and so I would consider that to reduce your stress. The reason I had to listen to it while going to sleep was because I really was not sure I believed what it was saying, but my sleeping brain took all those positive suggestions in and I started to be much more confident about birth.
Out of all the people you have talked too/seen, did any of them really resonate with you? Did you click with any of them? If so, I would say to work with just that person. You have too much advice coming in and I think you need to pick who is going to help you and work with them. Unfortunately, breastfeeding is an art (like medicine) and so everyone will approach things in different ways.
Hope that helps!
Our babies have the same birthday :)