Eeyoreloverforever -
Congratulations on your pregnancy! I hope you have a wonderful time at WDW. I went to WDW around the same point in my pregnancy - maybe 29 weeks? - and I had a great time. In addition to any insurance concerns, make sure you travel with a note from your doctor stating that you're fit for air travel. I think my doctor's note stated that I was fine to travel until a date which corresponded to the 32nd or 34th week of my pregnancy.
Having said that, we also made it the most relaxing WDW trip that we've ever taken. Since DS was 2 1/2 at the time, we returned each and every afternoon for a nap in our hotel, and I needed it as much if not more than he did. I made sure to drink lots of water, and took advantage of the times DH wanted to go on one of the "big" rides to sit down with my son for a snack, or line up to see one of the characters. I avoided all of the rides which Disney listed as being inappropriate for pregnant women, but that still meant that there was lots to do at each park.
Have fun!