Hi GreyBird84. I receive PIP daily living at the enhanced rate for solely mental health-related reasons. Before that, I was on DLA for ten years for the same conditions.
If you have read the form and consider most of the areas to be concerned with only physical problems, it may be that your illnesses do not affect you in ways that will qualify you for PIP, as I found it quite easy to look at the questions through the prism of mental illness. It is not the diagnosis, but how it impacts your life in the specific areas laid out.
If you need prompting and/or supervision for any or all of the activities, without which you really cannot complete them on more than half of the days, then you may score points.
It may help you to know that the reliability with which you can perform the activities is a major factor when considering whether or not you can perform them. So, can you (for example) prepare and cook a meal when required, to an acceptable standard and within a reasonable timeframe, ie not more than twice as long as a person without your condition would be expected to complete the task? If you can't, then you may be considered unable to do the task at all (although they are unlikely to follow that to its logical conclusion and give you maximum points in my experience. But you should score something).
The form is quite daunting and I recommend you look at dedicated forums such as Benefits and Work, Scope, Yourable, the benefits and disability sections of Money Saving Expert, etc. You can pay for full access to Benefits and Work and people say it's worth it, but I just read the forum posts. You could go to the CAB for advice; I got unlucky there with a pretty unhelpful individual, but many others seem to have received very good advice on how to best fill in the form to make it clear that their conditions affect their daily life and/or mobility in ways that meet the criteria to score points.
I filled in the form going into as much detail as possible, describing at length how my conditions affect me in each area. I also wrote a diary covering five days that laid out literally everything I did and how long each thing took me. I had no recent medical documents to send, though the support worker from my supported accommodation wrote a short paragraph for me and accompanied me to the assessment. That entailed going over all of the questions again and me just reiterating what I had written; it was unpleasant but the assessor was kind, and honest in her report.
I was terrified of being moved over from DLA, but it went quite smoothly and I got the award to which I was entitled, so not everyone has a bad experience. But I really drove home the issues around my ability to reliably perform each task, so that they had little option but to score me something on the relevent questions (not all applied to me)
I hope that is helpful.