Breastfeeding..natural?! Why so stressful?!

So my little one is 1 week old and is EBF. With my first who was formula fed this time around its so stressful. With formula you know they are eating what they need, how much and they take yo it easy also a nice routine is made. With breastfeeding it's so stressful and a worry. I express as well because 70% of the time she won't latch on and then tires her self out so she won't feed at all. When she does feed from me directly I worry she isn't getting no enough because I can't see what she is having. Plus I'm expressing and feeding directly so it's like I'm doing so many things. At night she will have a bottle of my expressed milk because at night she just wants to eat and not mess about latching on and then day I will breast feed directly but it then the worry. I don't know I just didn't think it would be so stressful