Moving from DLA to PIP, extremely nervous

I live in N.Ireland and I heard yesterday that a friend who lives close by has been contacted to claim PIP. I am on an indefinite award and am expecting the PIP process to start very soon for me and am feeling very anxious about it.
I have paranoid schizophrenia and to be honest I have been 'relatively' well for a number of years, have not heard voices in a long time and the last time I had a relapse was 2004....or 2006 (briefly while in latter stages of pregnancy). My psychiatrist discharged me 2016 as obviously she was happy with my progress. I am concerned about my chances for PIP on mental ill health alone - with my discharge. I looked at the different PIP questions, two that stand out are the 'mixing with other people' and 'going out' - on bad days its very difficult for me to even go out of the house to meet people. Once I also went without having showered for a week due to lack of motivation.... I always believed I suffer from social anxiety but to my doctors/former psychiatrist this was never really 'official'...as my diagnosis was originally schizophrenia. I also wanted to ask although schizophrenia would be the primary illness I'm claiming for, I had my left lung removed due to cancer in 2013, would it be worth mentioning that I get breathless walking sometimes, on the form - would that help my case? Any help/thoughts much appreciated...