Pip assessment on wed advice please

I have my pip assessment review on wed and I'm all panicky about it

Basically I'm 27 and I suffer from mixed connective tissue disease (lupus & Sjögren's syndrome) fibromyalgia, chronic fatigue syndrome and I have a arythmia and prolapsed/dehydrated discs in my back which is excruciating.

I am currently on steroids have been for a year and half because my kidneys keep failing without them I had to have rituximab March 2015 with the steroids to help with my kidneys they were so bad this resulted in me going into liver failure as the chemo just didn't agree with me although my liver started to recover by itself I was obviously very poorly so my first assessment was a home one I was in my pjs in a reclined chair as this is the only way I can get any comfort.

I was successful however my review is at a assessment centre and I have heard they are judgemental on what you wear to the assessment?

I do have a wheelchair (not a self propelled one) as my joints don't allow for this I try not to use it as I feel completely embarrassed in it because everyone tends to stare at me and makes my anxiety even worse will this go against me if I try to walk with the help of my mum?

I'm currently on methotrexate and hydroxychloroquine but the methotrexate is making me very poorly the rhuematology dep is considering taking me off it and trying something new because of this meaning I'm stuck with the steroids which give me swollen painful feet.

But despite the amount of pain I'm in I'm limited to tramadol and gabapentin at a controlled dose simply because my kidneys can't take anything more than this and anything stronger otherwise they will just go into failure for a 3rd time will the assessor understand this?

I worried they will just see me as a young female with not much wrong as all my illness is completely invisible