Hm? This character isn't Mary Sue-ing? Just cause she's smart and pretty and has a pet dragon doesn't mean anything, I mean look at twilight sparkle XD
A correct interpretation of a Mary Sue would be better shown as;
"Name; Darling
Gender; female"These would not make a Mary Sue. Name, and gender don't matter (Except if it were a guy it would be a Gary sue)
"race; alicorns"This can be seen as borderline Mary Sue only because alicorns are princesses... And there are supposed rare or royal, making your character an alicorn would be automatically making them either rare, or a princess/prince, which makes them look too perfect. Choosing a race besides alicorn is often the better choice anyways! There are plenty of them out there; pony, unicorn, or Pegasus, and those are just the pony type, you can't forget about the others; dog, draconequus, changeling, bat-pony, dragon, etc.
"Talent; making everyone love her"This is also on the borderline of mary-sueing, making everyone love her could be fine if you provide a negative trait that counters it (such as always feeling lonely because nopony loves her for being herself) not including that balancing act will make your character Mary Sue.
"she is smart and pretty. Can go as fast as rainbowdash. Is super strong and-Including
all of these is Mary-sueing, however two or three good traits is not your just listing the things she likes about herself~ (but be sure to include some things she doesn't like as well, such as unsocial, mute, blind, teased for talent, etc.)
"is celestia/discord/luna's daughter/apprentice"Try not to go this way... It is very strong Mary sueing... It's hard to counter these ones with negatives.
In the end just counter most positives and you should be fine ^w^
your character is fine as it is echo (you have clumsiness and living in the middle of nowhere on your side) ^w^ she looks adorable!!
What's her talent? ouo
Edit;; Oh ouo and I hope you don't mind me dropping off some gift art for you ouo