I remember the early days were very difficult and scary! My baby just used to fall asleep at the breast (and still does). I remember the first night we got her home, she can't have had much at all. She feel asleep when I put her on me every time, then screamed when we tried to lie her down. We didn't have any formula in as a back up, so my partner went out in the morning and got cartons. The midwife came that morning and said the baby looked a little yellow. The midwives and health visitors that came after that also said she looked jaundiced so we took her to the hospital on Christmas Eve. She was always very sleepy (with hindsight she probably was a little jaundiced, its common) so we also got her blood sugar level tested. Her levels were fine in both tests. I remember being told a calculation you can do, that takes into account your baby's weight. It tells you how much formula they should have over 24 hours. I remember noting down the times and how much she had drunk. I used to add up how much she had had. Ask your midwife or health visitor about that calculation. Are they still coming round?
My little girl was never that hungry and it was a struggle to get her to drink what she was supposed to. I remember she only used to take about 30mls a time when she was tiny (she was 6lb2 at birth). It does sort its self out though. At first we were told to feed her every 2-3 hours and we woke her as she was so sleepy. Then she started to cry for food herself. Then it went from 3 hours to 4 hours, now at 11 weeks its between 4 and 5 hours and she is lovely and hungry. When you're going through it, it is so intense, but remember its not for long, and when your baby is telling you they are hungry every 4 hours its so much easier. You know where you are and you can plan things again. Going out becomes so much easier.
By the way, bringing back milk is normal and its called possetting. It normally just dribbles back out of their mouths. My baby does that, she also has a reflux problem which is common too. She has sick dribbling out of her mouth in between feeds. Apparently they grow out of it and being on solid food helps. I have put books under one end of her crib and have her in her chair during the day, so she is more upright.
Make sure you burp your little one. Sometimes milk can sit on top of bubbles of air in their tummys. You need to bring the air back up or else they will get colic. They will often bring up a little milk when they do a burp and its better they do it when you burp them. If you don't burp them they will burp when you lie them down and bring the milk up then.
Also, its probably worth you buying in some Infacol, incase your baby gets colic. My baby started to squirm with discomfort and a drop on Infacol before each feed worked a treat.
Blimey, I've written loads! I hope some of it helps!