Congratulations, that's wonderful!
The early trip should be fine, just make sure to watch for things that cause you nausea, if it's certain things. If you get really tired (I was ALWAYS tired though both my pregnancies), take a break. Listen to your body, it will tell you when it's time to stop. Drink lots of water, eat as well as you can, etc.
The second trip I would check with your doc and make sure he/she thinks it's ok. I don't want to scare you at all, but when I was in my 6th month with my 2nd pregnancy I started passing out if I would stand or walk for more than 15-20 minutes at a time. Needless to say, there wouldn't have been a WDW trip for me! At 7 months with both my pgs I was forbidden to go any further than an hour from home by my doc. Ha! Little did she know, we went car shopping 2-1/2 hours away when I was 36 weeks along with the first one! Well, she did find out, because that's the same day I went into labor....it was actually back labor, and I didn't know it until 4 days later when I went to an appt complaining about my aching back! Probably would have happened anyway, but I started feeling pain about an hour and 15minutes into the drive! Something else to consider is how far of a drive it will be for you at that time; riding in a car can get very uncomfortable later in pregnancy if you're going very far. I'm not sure if they will allow you to fly at that point in a pregnancy or not.
All that aside, if your pregnancy is going well, if you're feeling up to it, if you can take it easy, relax, and not try to do everything, you should go. Your life will change in a big (awesome, but big) way not too long after you get home, and there won't be the possibility of a trip ilke this for a LONG time to come. I would take the docs phone # (including after hours # if it's different) in case you have a problem, and find out if you don't already know, where local hospitals are, just in case.
Enjoy your trips, and enjoy your pregnancy, it doesn't last long!