Kathryn, yes, she was the only (that we know of), and yes we know of her almost entirely by fragments. But there is a reason poets have revered Sappho for 2500 years: she was the best.
The moon has set
I lie in bed alone.
Some say the infantry,
some say the cavalry,
some say the fleet
is the sweetest thing on dark earth.
I say, what you love is.
(Both translated by Jeanne Safer)