My daughter is almost 6 and still loves princesses although we've been to DLR enough now that the novelty has worn off a bit. That said back when she was 2.5-3 it was ALL about meeting princesses! I commented in a similar thread, so I don't know if you read that, but here's some of my advice:
1. It is possible to meet all of the princesses in a 2-3ish hour block. You have to plan really well but it can be done. Check the app the day before to get a good idea of where they meet, and what times, and make a plan. Check the morning of to solidify your plans. When we have done this it went something like:
9am - ariel at wishing well
*move to back of the line once you meet her
9:30 - ariel switches out for aurora, by this time you should be at the front again
9:45 - belle in fantasy faire
10:10 - jasmine in the oasis
10:30 - tiana in NOS
11:00 rapunzel in fantasy faire
etc etc etc. at some point you will probably also want to do royal hall, do not wait more than about 20 minutes. if you go during/right after the parade, you can get in in about 10 minutes.
park hop to anna/elsa, the wait for us has consistently been 20-30 mins regardless of time.
the goal is to be at each meeting place 10 mins before the princess actually gets there - that way you are 1 or 2 in line and it goes fast. every additional person you are behind adds a couple of minutes and throws everything off.
2. have an autograph book - skinny crayola markers are the best for this. Have it open to a page ready for her to sign when you go up.
3. no matter how princess obsessed she is, she might freak out and/or be very awkward. it's ok, she'll still love the pictures afterwards and forget she made it totally awkward

4. have at least a couple princess dresses to choose from, we usually take one per day. have one that is shorter/less bulky that is more ride appropriate (for us this was fawn.)
5. the shows at the royal theater in fantasy faire are super cute, and they let the kids sit up front which they love.
6. our kids are 5, 3, 1 - we take a double stroller and most everyone still takes a nap at some point during the day. we don't like going back to the hotel, but they definitely need naps or everything is miserable. even with naps they crash hard, so don't plan anything big for 8pm+ (our kids have slept through WOC every. single. time)
7. their favorite part of disneyland is honestly probably the parade.
8. we didn't do a ton of big rides when we had no one over 40", but the rider switch is really easy and good for the whole day - so you can go back if you want later, if not, whatever.
9. our 3/1 yo are boys. our daughter likes cars land, probably more now than at 3 though. if it weren't for our boys, DCA would have way less for us to do. when she was our only mobile kid, out of a 4 day trip, DL would be 2.5-3 days and DCA would be 1-1.5. Ariel's grotto, mermaid ride, monsters inc, disney junior show (which I understand is closed right now) was kind of it.
10. bring lots of snacks!!
Get as much done in the early mornings as you can! A lot of those silly fantasyland rides have painful waits in the afternoon (25 mins waiting for dumbo is torture.)