Is your OC a Mary sue?

Mlp oc- Princess Starshine crystal.

Name: Princess Starshine Crystal, but her sister calls her Star, or, when she wants to annoy her, Shi-shi.
Um, you need to work on that name.

Age: 13
*Cri*
Race: Alicorn
WHY MUST YOU DO THIS
Relationships: She doesn't have any friends, besides a handful of crystal ponies she nods in passing. This isn't because no one likes her, but the fact that Starshine is simply a very private pony. Besides that, there is Princess Cadence (Mother), Shining Armor (father), and Princess Flurry Heart (sister).
(ノ'n')ノ彡┻━┻
Appearance: Coat is relatively dark shade of purplish pink. Mane is in wavy clumps of very light and dull pink and lavender. Blue eyes, dark blue, small framed, rounded glasses.
Not to much Mary sue I guess.
Cutie mark: Currently, she's a blank flank, but I have a vague idea of what I want it to be.
Thank you. Just, thank you
Personality: She's an introvert, preferring to seek her own company rather than that of others. She delves herself into her studies in order to discover what kind of magic she excels in, and is therefore princess of. Whenever she is required to attend a formal event, she plasters on a half-smile and tries to get out of there as soon as possible. Star holds fierce determination and perseverance, but she is rather close-minded. She has a habit of viewing others with contempt, generally reserved for those she believes are naive, or simple. However, she is surprisingly loyal, especially when Flurry Heart is involved. After all, she is her best friend, and, much as she denies it, she isn't sure what she's do without her.
I'm sure there's NO other purple princess introvert whose only friend is her older sibling and prefers studying to socializing.

Backstory: When Starshine was born, her wings weren't like that of a normal alicorn, or even that of a pegasus. They were incredibly small, and it became evident that she would never be able to fly. Still, Cadence and Shining promised to love her the same as Flurry Heart, who already had flight skills akin to that that of a normal adult pegasus. Star's disability bothered her when she was younger, but she's come to accept it, and now it barely even crosses her mind. Sheltered in the castle for much of her young life, she didn't venture out much unless forced to, and even then, she pretty much ignored all the other fillies. She idolized her sister and mother when she was younger, like all well-brought-up small children do, until her views branched off from theirs. At that point, Star began to disregard the two, which morphed into disrespect bordering on rude. Eventually, she would tell anyone who would listen that, "I want to become like Celestia and Luna. Their work has real meaning, unlike Cadence and Twilight. I mean, how much power can something as abstract and debatable as love and friendship possibly hold any power? It's just propaganda to disguise the fact that they aren't actually doing anything. Seriously, when was the last time you saw my mom doing work?" Word of this eventually reached Cadence, and in response, she sent Starshine (Along with Flurry Heart, who begged) to Ponyville and the Mane Six to learn about friendship and its importance.

Commentary: she is a copy of Twilight, she is related to the main princesses, she's an AlICORN Jesus take the wheel.
The only thing non Mary sue about her is her wings.
Mary sue level: 99%