PIP is it worth bothering? It's a headache already

How long is the PIP process?

I phoned up to request a form a few weeks ago and set up all my security details. The lady on the phone was very nice and said the claim form would be sent out and to ring back in a few weeks if it doesn't come. 

It hasn't come so I rang up and they now say they can not verify who I am and I must have rung 3 times today and not gotten through the security questions. This is the first time I have rung in a few weeks. Then I get a phone call back and they can not verify who I am through the national insurance number and I now have a different set of forms and not the original one they said I was getting. Unless the person on the other end of the phone made a typing error I don't understand what is going on and am now in tears with the stress. 

Given I have autism, fibromyalgia and permanently borderline anaemia even though I am on supplements I don't even know if it is worth going through the process or not or whether they will just say no as I can manage to work (through necessity not choice).

All I want is a little bit extra so I can get some extra high quality supplements and get my bills down so I can maybe drop a day or two at work so I can feel normal again and not live between fibromyalgia relapse and autism meltdowns all the time. But that is obviously too much to ask of life right now I just feel so hopeless and doomed to this cycle forever.

Julie