DD dresses herself now but I still do it often as we are usually running late to be somewhere LOL. She can put her shoes on as long as they're either buckle up or velcro, nowhere near ready for shoe laces yet (she has just turned 3 a few weeks ago)
knickers go on backwards quite alot but she sometimes remembers that "the tag goes on the back", she's really impressed me alot over the past month or so.
She's been fussy with what she will & wont wear for about a year I guess, maybe a little less?
I personally dont think you have anything to worry about at age 2.5yrs but I would try to encourage her to try doing it herself now & then, she'll probably enjoy it too