When will poetry be finished?

I'm writing a series of poems about my sister, who died in 1999 on her thirty-sixth birthday. I spoke to Sarah almost every day, and we both had a sounding board, someone we could tell anything to. I miss that. So I'm writing about her but I start with a huge rambling freewrite that somehow falls into lines, then I trim and sort and try and make a poem out of it. I was on Betsy Lerner's website this morning (see blogroll) and someone had quoted Paul Valery translated by William H. Gass: 'No work is ever done but only, finally, in grief abandoned.' That's exactly how it feels to me. 

My first draft was 38 lines of rambling, some lines I just liked the words (like using suckered for starfish, as they have little sucker feet) and some felt emotional to me, like 'did she leave an oval in the sand?' I did wonder if the following line: 'Is one of these depressions hers?' is too obvious but played around with it. 

I ended up with (first 8 lines):

We tread between starfishes
suckered onto the harbour sand.
Hermit crabs patrol the tideline
shells casting long shadows.

My sister played here, between jelly shoes
and sunhat, collecting shells
and sea-frosted glass, into patterns
that wash away as memory hollows.

And so on. Now I'm fussing over 'long shadows' even though that's the main memory, all marching in the same direction, the late evening making the shadows extend into what looked like bar codes along the shore. I'm mixing the muddy harbour with the sandy one where I live too, poetic license. My sister adored the sea, swam in all weathers, we shared a love for the beach in rough weather too. When we both had babies, we would get a friend to babysit at high tide on windy days, go down to the nearby beach and throw ourselves into the rollers for an exhilarating hour like children. Then back to sensible, earth bound activities like nappies and babies. I remember her absentmindedly pulling out a breast for her baby son, circled with flattened seaweed. I miss her.