Hi,
I breastfed my daughter from birth until 15 months. I always had a constant worry regarding whether she was getting enough milk and I think no matter how much research and leaflets you read, how many experiments they do, there will always be a constant niggle in a mothers mind. You can't measure the exact amount of milk that a child is getting when breastfeeding whereas in bottle feeding you can - so how do you know your child is getting enough?
My daughter fed in short periods but often, I just went with "go with the flow".. literally. I had it easy breastfeeding, she was a great latcher and I never had any issues (and she was my first (and only) born).
Who is to say what is "normal" and what is not? What good are charts and facts going to do really... every child is different and I think a parent knows their child, sometimes we have to be reassured that we are doing a good job, they are gaining weight well and the breastfeeding should continue.