Sleep and too much reading

There is way to much information out there about infant sleep patterns. In trying to get Sadie established on a routine, which is supposed to be good for her, I am going crazy with all the information you can find. Right now she sleeps for 4-5 hours for one sitting, wakes up, takes forever to go back to bed, then sleeps for only 2-3 hours and then is up for the day. Sometimes she is up more than that but never less. So all these books say she is old enough at 6 weeks (she is now 7) to need to be on a routine. plus routine helps her as cranky or fussy is usually due to lack of good sleep. Now she should be able to start self soothing or is it after 4 months old? you see I just can't tell. apparently the sooner we start the better but who is to say that she isn't waking up starving? As far as I can see that is exactly what is happening as she wakes up, sucks down a bottle then can't fall back asleep. The child likes to eat! how does one tell if their child is hungry or not? All the books can tell you is that yes a child between 6weeks and four months may wake up for a midnight feeding. an even after that between four-9 months they may still wake up for a feeding occasionally. Ok then so is she not getting enough sleep because she has to wake up to feed? Are we supposed to feed her then put her back awake and let her cry herself to sleep? She is only 7 weeks old people. Some say not to, some say to start early, some say to start early but don't expect anyting till four months old. My gosh a parent can go crazy reading this crap. All i want is my daughter to get enough sleep so she is a happy baby. Is that too much to ask.