Congrats!!
I was just about in your situation during our trip 2 years ago. I found out right before our trip and was about 5 weeks along when we went.
As far as morning sickness goes, 5 weeks is usually too early to have symptoms, so I was able to eat pretty much everything (the nausea hit a couple of weeks later...whoa)
And as far as rides go, I probably shouldn't have gone on some of the ones that I did but I had absolutely no problems afterward. I went on everything except M:S, SM, TT, Goofy's Barnstormer and Star Tours. I basically tried to avoid all of the ones that were real bumpy and jerked around a lot. I did go on RnR and ToT because I felt like they would give my stomach that "falling feeling" but were fairly smooth rides.
Ironically, the most severe warning for pregnant woman in all of Disney is for Goofy's Barnstormer...there are signs everywhere!!
And one amusing tale...when I worked at WDW I worked at Body Wars in the WOL pavilion. If we saw a woman who looked like they were expecting, we were supposed to ask them if they were expecting and if so, try and persuade them not to ride.
Well...I never really asked unless they REALLY looked pregnant. But I asked this one woman and she wasn't and she had an absolute fit!! It was the most horrible, embarrassing moment and from then on I never asked another woman that question again!
Good luck and have fun...
