Seaming Green Grass

I seamed this weekend, all 12 seams. Even started weaving in the ends... and then it occurred to me that I should try it on to see how it fit. Do you see where I might have gone wrong? It didn't fit. Fine. But then trying to undo the seams (which, by the way, looked SO perfect and...sigh...) when the ends are tucked in - a little bit of a disaster. It took two days to undo to a point that I could start to fix. The arms need to be longer and MUCH wider. Really, it would have only fit the arms of Misha Barton the first time around. The deadline is in one week. Can I do it?