First of all, congratulations! How exciting!
You can check on the Disneyland website for a complete list of rides that she should be able to enjoy. The Fantasyland rides should all be fine, as they are more of the "tamer" rides. There are also signs posted outside on each attraction that could pose a health risk to pregnant women or people with heart problems. You can absolutely bring snacks and water into the parks. We always bring snacks and plenty of water into the park, and never have a problem.
If I could make a suggestion to you guys, if she ends up not being able to ride very many attractions, enjoy some of the many shows and entertainment that they have at the parks. Disneyland has the hilarious Laughing Stock Co. at the Golden Horseshoe, Captain E.O., Soundsational parade, fireworks spectacular, Fantasmic!, Innoventions building where you can play video games, etc. California Adventure has the very cute "It's Tough to be a Bug!" show in the theater, the amazing Aladdin musical spectacular in a theater, World of Color, Pixar Play parade, and the Off The Page building (I think that's what it's called) where you can hang out and draw and explore. These may even be better options if it is quite hot outside, and most of these buildings are air conditioned, so that you guys can catch a break.
Hope you guys have a wonderful time!!!