nup, it doesn't sound like Plath. She doesn't write crap like that.
Although the only similarity would be the slight angst, but that's it.
"I have no words, no tears".
hhhmmm, Plath went through peroids of severe biological writers block, but the language lacks the Plath substance.
"My heart within in me is like a stone"
oh god. bad poetry. nuff said.
"Look right, look left"
no way is this plath. This sounds like what an angsty teenager would right.
"no everlasting hills i see"
Plath is NOT a romantism (whatever it is) writer. None of her poetry resonates with this. She would have thought up stronger imagery. "Hills" is pathetic. Honestly, unless she wrote this when she traveled with Hughes around America "hills, lakes, cabins" trip.
"My life is like the falling leaf"
A bit better. Stronger through fragile impressions. But nope, This doesn't suggest that it was written by plath.
"O Jesus, quicken me."
Nice, could quite possible be.
I have so much respect for Christina Rossetti, and I don't think it's written by her.
Possibilities are that it was written by either, when they were very young. It could be from Plath's juvenilia. This would have to be checked in the Smith College archives. I just checked Plath's "Collected Poems" and it's not there. By first impressions, I guessed it wasn't Plath. It lacks in so much. I don't think it's a good poem at all.