For me the problem here is, that it looks like she doesnt wear a bra and as if the connection to the body is like she wears some garter with fake breast.
Either its the fold of the shirt being misleading.
The reference was someone with sagging boobs, trying to anti-sagging.
Or the artist is a virgin.
And i dont say the artiost is bad, just some anatomics that looks weird to me too.
I agree. Make her chubbier to fit the breasts.