Re: Question about timing and weight
I gained exactly 40 pounds with both of my term pregnancies. DD was 7 lbs 3 oz and DS was 8 lbs 12 oz (neither were post-C-section, just illustrating how maternal weight gain has little to do with resultant size of the baby).
For timing between births, 20 months is fine. DH and I wanted to try again ASAP after our c-section (given our situation and my age and our desired family size), with still the good chance of a VBAC, and we talked to several doctors about it. The longest that any of them recommended was 18 months between births. We hit it on the first try this time, so if I get all the way to 40 weeks, there will be 13 months between births.