That's so sad, Tumblebug, Lots of love to you.
Innocent - I think it's probably a good thing that you have The Fear, I was gloriously, ridiculously dreamy and unrealistic about the impact of having a baby. I imagined us snoozing together in my bed in the afternoons, walks in the park, days on the beach - I did not anticipate how hard it would be, and as a consequence I was shocked and dismayed by the reality.
Your fears are completely legitimate. You have a life that you presumably enjoy, and it is going to change. Pregnancy is quite hard work and very anxiety-inducing, childbirth is incredibly painful, and parenting is hard work and draining and sometimes excruitiatingly boring. I'm not trying to scare you, I'm just being realistic!
But, having children gives you something that I can't quite describe. Suddenly everything makes sense and is put into perspective. Being a parent is pretty awesome. I find my children fun, funny, interesting, gorgeous and delightful - so much so that I want to have a third.
Also, I think if you don't actually 'try' to get pregnant, it can be a bit of a shock! My advice is keep talking about how you feel. Some people do get pre-natal depression, so it's important that you keep talking. Also do not forget how important your relationship with your dp is, and now more than ever, you need to invest time and effort into it. My relationship with my dh was very easy before we had children, so we failed to make an effort until we reached crisis point (sometime after dc2) and then we literally had to work our arses off to bring it back from the brink.
I hope that makes sense. Just my opinion - and I'm sure others will have stuff to add!