Can I offer some writing advice?
My name is Miya Viyor, the second princess of the kingdom of Viyor. Although we’re not a particularly large country, our royal name has a considerable amount of prestige as a result of its age.
This is the kind of sentence that makes me want to stop reading something. If I picked up a book off the shelf at a book store and saw this on the first page, I would immediately put the book down.
This line is pure exposition. It gives me facts while accomplishing anything else. One of the most basic skills of a writer is figuring out how to convey facts while embedding it with something more interesting (and sometimes, even more informative). Before I care about a character's background and profession, I need to care about them
as a person. Give me some aspect of their personality or voice or something that would let me identify this character without any information about what they look like or what their profession is.
To give you an idea of what I'm talking about, here's how I would re-write that intro:
Being the first-born daughter of royalty is overrated. Second-born daughter, now that's a nice place to be. I get all of the comforts of royal life without the crushing responsibilities that come with being a future queen. And in the kingdom of Viyor, even "second princess" is a title that caries prestige, specifically the kind of prestige that follows a family name that has long history of sitting on the throne.
(I'd actually go one step further and say something like "200 year history of sitting on the throne" or "sat on the throne for however many number of generations," rather than saying something ambiguous like "We've had a long reign.") That's not the best example, and it probably deviates from the personality that you had in mind for the character, but hopefully it's enough to get the idea across. I don't intend to claim that my version of the line is particularly well-written, but at least it sounds somewhat like how a person might talk, and it conveys a bit of her attitude toward the situation she's describing, as opposed to a line that reads like a Wikipedia article with the phrase "my name is" inserted.
The next paragraph is a bit better, as it at least hints at what what one of the main conflicts will be (or at least, what one of the main dimensions of the "older sister" character will be). But still, telling me that our protagonist's older sister has been burdened with being queen feels very much like plot, not character.
Now, as for this part:
How she managed under those circumstances and still watch over our little sister and I is beyond my comprehension.
I like this. This line is actually the first point at which I feel like I'm seeing the story through our main character's eyes. I'm not just getting a list of facts about the situation; I'm now learning something about the main character's emotional state. We're learning that the main character's older sister kept watch over her all those years, but more importantly, we're learning the main character's reaction to this: she's astounded that her older sister has held up this well.
Always keeping a smile on her face as the two of us wandered around the castle bothering servants when we were little, she had a much greater maternal presence than our actual mother.
I also like this. It paints a picture of a scene: I'm now visualizing two little girls wandering around the castle, bothering the servants as the older one wears a smile on her face. That puts an image in my mind. Compare to the first paragraph I quoted, which reads more like a bullet-point list of facts.
Oh, and as a bit of an aside: it feels really weird that our main character has a name and her sister doesn't. Actually, if anyone is going to go nameless, I kind of think it makes more sense for the main character to be the nameless one, as there are plenty of first-person stories out there which have a bunch of named character and then a viewpoint character who only goes by "I." I'd just go with whatever feels natural, and to me, it feels really unnatural for the older sister to not have a name (almost like you're going out of your way to avoid naming her). Maybe there's a reason for that I'm just not aware of.