Hi Alex
There's nothing to stop you from sending in additional evidence if you think it is relevant. Just be aware that they are making a judgment on how you were at the time you filled in the claim, not how you are now.
If you are worried about the length of time your MR is taking you can give them a call, though they can take up to ten weeks.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems