I have a similar story in that I tried and tried for ages to conceive dc 2, having 2 miscarriages along the way which were terrible. Eventually I got pg and because of my miscarriages I didn't really think about it much, I was pretty much in denial.
It really only struck me that I was going to have another child when I was about 25-30 weeks pg. Suddently I was so so sad about not being able to be there for my ds. We have such a close relationship, loads of cuddles and chats. He was only 18 months old when I got pg, still just a baby and I was so sad that I was going to make my baby the older brother. I felt like I was going to make him grow up too fast.
I didn't really tell anyone this (apart from my best friend who was also pg with her dc2) and did my usual brushing it under the carpet trick. When dd came along, I can't pretend it wasn't hard work. She's totally different to ds, whereas from about 10 weeks he would have a good solid 2 hour nap during the day, plus another one later in the day, she barely slept at all in the day, and badly at night. He was always very chilled and she's much more clingy.
The first year was really tough, but you know what? I am so glad we did it. My sister said to me "you've given him (ds) the best present you could ever give him, a sibling". And I think she's right. I'm so glad that God forbid if anything should ever happen to dh and I, ds has someone who loves him as much as we do (and vice versa) and will always be there for him.
Dd has been great for ds too, he's really learnt to be more considerate and gentle (not easy for a toddler). You do have to try and make sure you spend time with each child seperately, but I think that makes you focus much more on ensuring that time is spent well. When dd went for her naps, I would really make sure that rather than using that time to tidy up etc, I would do some painting with ds, or playing lego with him. Those times became really special. Now ds is at pre-school, I'm able to have those kind of special moments with dd too, we sit and have our girlie afternoons reading books and doing puzzles. They've become very precious moments.
Don't worry that your ds didn't sleep much during the day, your dc2 may well be completely different. Mine certainly are. And having dc1 at school most of the time will make such a big difference. DS was 2.3 when dd was born and still in nappies, so it was tough. I do sometimes envy those who were able to space their children out a bit more (age was a pressing factor for me)
Oh and ignore those friends who seem to make having more than one child look easy. Everyone puts on a front most days don't they? I'm sure they have their fair share of days when they don't manage to get out of their pjs, and have bits of old food stuck in their hair, just like the rest of us!