PIP Review Form

I am mum to son who has been on Pip for the last 10 years. I am currently filling in the review form for him as he is unable to do so. I am finding the whole process overwhelming, I've got a 2 week extension. I had the day off work yesterday to sit and do the form I was trying to do it from 9.00 am until 2.30pm and feel I hardly did anything. I have read the guide on here and looked at information online. I feel totally disorganised,
Nothing has changed since the last review but it doesnt seem its good enough to just put no change, I have to go through and list everything again, the whole thing is exhausting and really stressful and I'm not even the one with the health issues!