That's such a great line to work with, nice choice!
Overall it's going into the right direction, but I'm not too sure about the finger point being that long. Finger points are a bit generic to begin with, so it's good that you keep it going with it in order to make it different. But after x43 I would take that hand/arm back with more pain exhaustion. Right now it's going back in almost the same rhythmic motion that is visible at the beginning, so it's a bit repetitive.
The way I hear the line is that after the first "I'm not the woman you say I am..." she kinda breaks down and then collects herself to say "I'm not that woman." at the end. So during that pose, I would play it out more like she's struggling with her emotions and trying to control herself, then she says that last line (which you could act out with her being stern again, or breaking down). I personally would go for stern again, but that's up to you. Right now though you have her looking right and then left during that pose, which is a bit too "search-y" for me, as if she's searching for the words, as opposed to trying to regain control of herself. And the very last frame, watch that pose and expression. It looks like she's sleepy, or drunk or on drugs. :) The intensity of the audio is missing in that last expression and pose, so I would listen to that part more closely and push the emotion at the end.
I find that after this stage I go into linear or spline mode and the feel and timing of the blocking gets lost, do you have any advice to advice to avoid this?
Regarding the feeling of losing the blocking timing. It's the pitfall of blocking things out in stepped mode. Going pose to pose will give you sharpness and accents but if you spline it all that will get diluted. You will have to have a clear vision of how the acting is supposed to be and once you spline it go back in there and add more breakdowns and work in segments. Go section by section and re-time the beats. What helps me is to blocking things out in linear mode and add spline mode from the get go during sections where I know that I will have it anyway (like during a swing, or jump or anything arc-y). At least in linear you will see how long each transition from pose to pose takes and how it looks like. If you don't have enough breakdowns in stepped mode then you're going to have to block things in after your initial "blocking". Your goal should be to have the exact timing in your blocking, so that when you go from stepped or linear to spline mode your animation doesn't change dramatically.
Hope that helps!