She is an oppai loli, I know retards in these threads get really autistic about terms. Guy for months got angry about Shamiko's glasses, and for years now some guy has been angry about "Thin books" even though he admits the translation is entirely correct, but because its correct he feels it'll be misunderstood by other people for being correct, when he wants to headcanon it as something else
Almost all of Shamiko's art on Pixiv is labeled as oppai loli, not as the term you want to use that you're pretending they use as a gotcha. Shamiko's art is almost all tagged oppai loli, like 90% at least.
Americans are super scared of that term so they create dozens of other terms like "shortstack" so they can run away from it. They run and hide "doesn't count doesn't count, don't call her that, how dare you call her that, doesn't count, I prefer this American term because I autistically hate that other term, stop" Just like loli, its more of a body type rather than an age. Even Mikuru from Haruhi is called an oppai loli type girl in Japan. In Haruhi itself they even talk about how Mikuru has a loli-loli type face with big boobs, so the term isn't misused at all. Americans just don't get how Japan uses terms, and get really autistic about it.