You have to get to know your baby - 2 months in it will be very different from Day 1, as you will just have had time to get to know your baby and what they want/need!
There is a big difference between a newborn and a three month old. It gets much better, they get much cuter and more predictable, more communicative and expressive. Remember this when you are two weeks in, struggling with feeding maybe, tired and emotional. It's not going to be like this forever!
You are going to have a moment, a few days after birth, when you really feel like you can't go on (with me it was trying to go to the loo for the first time after a third degree tear, with toddler DD moaning and baby DS crying, all at the same time). I sobbed and sobbed to DH who, now being an old hand, made me some tea and patted my head.
You had a hard pregnancy. This is good in a way, as the harder the pregnancy the easier the newborn phase - all those ladies who sailed through pregnancy are about to get the shock of their lives. You have suffered already though and are used to it!!!
Breastfeeding, if you do it, is probably going to be hard for the first two or three weeks. I was lucky with my two - feeding went well, they gained weight as they should have etc etc. It was still painful when they first latched on and hard work at first. If you do bf, stick with it if you can. Once you are through the initial period it is great and so convenient.
It's trial and error. If baby cries - just try everything. Is he hungry? Is he too hot/cold? Has he got a dirty nappy? Is he lonely? does he want a cuddle? Is he overtired and overstimulated? Does he just want a quiet feed in a dark room to doze off? Is he bored? Try moving to another room/chair?
In terms of the responsibility, the huge transition from non-parent to parent is something you just have to go through. Basically you are moving from a state where you are the agent of your own self directed, life, pretty much only responsible for yourself. Once you have a child, you move to always thinking about someone else before yourself, being responsible 24/7, always coming second to their needs. Its a huge change.
My second child, DS, is now3 months old. The days I have just him are a doddle - I wonder what I did with just DD! But the answer is your first baby takes up all your time because you are constantly preoccupied and getting used to parenthood for the first time - which you don't have to do second time around (there are other challenges but that is another story!).
Its a wonderful journey - if you feel daunted remember that even in the darkest hours of parenthood (there will be some!) no-one would change things for the world as there is nothing quite like your own little child!