Saw your post and wanted to sympathise but I am afraid I have no advice. Maybe the Bliss boards could help? FWIW I had DD at 38 weeks then DS at 34, so it is not a given that you would have another premmie. Could you discuss with a consultant perhaps? Do they know of any factors that might have contributed to preterm birth?
It's been a long old time since I left a post on MN but like you I am trying for number two, I'm pushing 41 and the last time I was pregnant my waters broke at 28 weeks (I was induced at 34 weeks). DS is doing very well though. I have big worries too because it was a difficult time but I figure that it is a risk worth taking. The only thing I think I can do differently is to not travel anywhere . Oh, and I'm convinced I need to drink more water for some reason, probably because it kept leaking out! The doctors told me there was an increased risk of PPROM in a future pregnancy but equally it could all be fine.