Hello Ashley! (great name, by the way)
How very exciting to plan a first trip for you and your daughter! I cherish so many memories I've made with my daughter at Walt Disney World. I can not wait to take some mommy/daughter trips of our own in the future. My mind reels at all of the wonderful things we could do together.
You should just miss the Spring Break crowds on those dates as Easter isn't until the end of March and a lot of vacations don't begin until the middle of the Month.
For your first trip, I suggest making it extra-special. I'm not sure of your budget, but I'll suggest
Disney's Port Orleans Resort-Riverside for your accommodations. If you can, definitely try for the Royal Guest Rooms. They are amazing and perfect for a seven year old girl! The resort is fabulous as well with great pools and boat transportation to the Downtown Disney Area.
As for dining, I would make one or two special Advanced Dining Reservations (depending on your daughter's tastes and interests) and then eat at the amazing Quick Service locations for the rest of your trip. The Disney Dining Plan probably wouldn't t be the best option for this type of trip, unless you really plan on doing a lot of Table Service meals or Character Experience Dining.
It will be awesome to have just two of you on the vacation because you can really do what you want, when you want, without the worry of keeping a whole group of people happy! That will be the most amazing part. You can let your daughter take the lead and spend a whole day doing whatever she chooses.
I'd be happy to help you choose more specific options if you'd like! Please come back and ask me any other questions you may have. I am so excited for your trip!
Pixie Dust,
Ashley