"Mom" and "mother" and the other variations are all common enough that alternating between them probably won't be disruptive.
On the other hand, they are different, with nuances of formality and attitude - so if you're alternating between all of them, with great frequency, like you do in this sample - then yes, it does start to feel a little weird. I think the answer is: you aren't limited to just one, but also, don't treat them as freely interchangeable.
My best advice is to point you at this previous answer of mine, I explain some general guidelines about consistency in labeling characters in a way that's appropriate to point-of-view.
But here are a few more thoughts specific to your particular case.
It would be a little weird if Quorraline, when addressing her mother, would sometimes use "Mother" and sometimes "Mom." I'd expect one of the two to be the baseline the mother's expecting, and the other to feel either too formal or too casual.
On the other hand, I have no issue with Quorraline addressing her mother as "Mother," but in the privacy of her own thoughts, or discussions with friends or siblings, referring to her as "Mom." That'd even give decent justification for sometimes referring to her as "Mother," even privately - she can think of her mother in both ways.
"My mother" or "my mom" is a little different: it's using "mother" or "mom" not as a name, but as a role. (This might be a little confusing, because they're so close - "mother" vs. "my mother".)
When you write
"Mactaurum," My mother called, that strikes me as odd, because you've already introduced the character to the scene, so it seems weird to refer to her by her role instead of just using her label. It draws attention to the role, the relationship, where that doesn't seem particularly pertinent.
I'll use a different example to demonstrate. Imagine we're already in the middle of a scene, where Captain Elijah Peterson, who is also the narrator's lover, is calling out to a new character named Mycroft.
"Mycroft," Elijah called; he always notices the instant somebody steps on the bridge.
"Mycroft," the captain called; he always notices the instant somebody steps on the bridge.
"Mycroft," my lover called; he always notices the instant somebody steps on the bridge.
Using "Elijah" makes sense here, because that's the narrator's personal label for him.
Using "the captain" sounds odd, though, because that's probably not how the narrator thinks of him, even though he's very much in "captain-mode" right at the moment. "my captain" might work, though.
Using "my lover" sounds odd too. Even though it makes sense for the narrator to think of him as "my lover," there's no relation between calling out to Mycroft and being the narrator's lover. The juxtaposition almost forces the reader to read this as a connection, as though the narrator is implying how attentive and caring their lover is.
In your piece, the "natural name" or label is "Mother" or "Mom." Whereas "my mother_" and "my mom" put focus on the role and relationship. This works fine in your earlier use:
My mom's an oceanographer and wanted to name me Corral -- because there the relationship is obviously relevant. But when calling out to her brother, it isn't.