Congratulations!!!!
Heck...I was in labor with my second son at DL. I had him the next morning.
Anyway, just keep yourself hydrated as you know. We went to WDW when I was 4 months pregnant with #1 and I started to swell up. Since you just found out, you probably are much more mobile than I was at WDW. I was able to ride quite of bit of rides during 1st trimester including POTC. That attraction does not limit pregnant women at either DL or WDW. I would stay away from all the coasters and anything that spins - but that was just me. As far as the other theme parks...count Magic Mountain out and Knott's is ok but you won't be able to go on most rides as well. The zoos and Sea World are fine but just remember keep hydrated and pace yourself. I was able to do anything while pregnant with #1/2 but when I was pregnant with #3, all my muscles seemed to give out and cramp on me no matter what and that was while I was 2 months. Assuming you are coming here during the summer, it can get hot in DL and humid. Don't know what the summer holds for us here but last year was quite awful with 100+ on many days.