Hi there Owen!
Welcome to the Disney Parks Moms Panel. I'm delighted you are heading to the
Happiest Place on Earth with your toddler. We just returned from a trip with my three year old son so I definitely understand your concerns. Since the Disneyland Resort is a family resort, I have found that Guests in line around me are very understanding in situations such as this. Often I have had to run to change a diaper or get something from our stroller and return back in line with my son. I will usually kindly let the Guests behind me in line know that I have to leave and will be right back, and I have never had a problem.
Speaking of potty breaks, your daughter may really enjoy the toddler-sized toilets in the
Baby Care Centers located in Disneyland Park and Disney California Adventure Park. They definitely made my son feel more independent on our vacation.
Another wonderful opportunity to take advantage of now that your daughter is three years old is the
Bibbidi Bobbidi Boutique in Disneyland Park. Here you can make her an appointment for a royal princess transformation. Even my son loved this experience when he did "The Knight Package." It's a way for kids to feel even more a part of the magic at the Disneyland Resort.
I hope this helps, and have a Fantasmic day!
-Jennifer