Congratulations on your pregnancy.
I have just had my second (both boys) and there is 17 months almost to the day between them. We too planned it so they were close. My pregnancies were slightly different, although this is hard to pin point as I didn't get morning sickness or any other discomforts other than an ever increasing waistline.
I found that second time around you just know what's going on in your body better. I felt the baby move earlier (because this time I knew it was the baby, not just wind). Also, for me, giving birth was easier second time around, because I knew what was going on. I too found it hard to gather information on second pregnancies, as most info is designed for first time mum's.
I would have to say that (for me) it is easier to have two young children than to be a first time mum again. Zac (my 18mth old) is a lover of routine, so all our days follow a similar routine. Wake up, play, breakfast, walk, snack, play, SLEEP.
Wake up, play, snack, play, dinner, bath, SLEEP.
Well, I hope this helps you a little.
Susan, WA, 2 boys (18mth & 2 mth)