I really think that you would benefit from seeking some decent support to manage your feelings around your health problems. I'm not saying this to be judgmental, I have chronic health conditions that have ricocheted my world and I have had therapy for it. If I could afford it, I would return again too because it is damn hard.
From what you've posted on this thread and others, you come across as very concerned about your health needs. You have seen specialists and had tests and - to an outsider - it seems like you're struggling to come to terms with the diagnosis that each specialist has suggested. CFS, Fibro, IBS and similar are bona fida diagnoses that would benefit from research to understand their etiology better but as it stands, they are not wishy washy 'labels'. They are collection of symptoms that make up poorly understood syndromes and often co-exist.
I've noticed on online forums that people get confused with this autoimmune label. The diseases are all so very different hence why you cannot have a general unspecified autoimmune disease, it doesn't mean anything. Even undifferentiated connective tissue disease (UCDT) has a specific set of signs and symptoms. The common ground with them all is that the immune system is over active and that very often, immunosuppressant medication is needed to prevent tissue damage.
Perhaps it's time to focus on improving on your quality of life and living with your symptoms rather than seeking out an elusive dx that probably will never 'explain it all;. Life is rarely like that. I developed a GI condition after years of a physical illness and I so desperately wanted them to be related. I didn't want yet another condition but bodies don't play ball. We are humans, we don't fit neatly into little boxes of symptoms and diseases.
I'm not saying this to be nasty. I am not denying your health problems. They are real, you have been diagnosed. I just am not convinced that this search for a diagnosis is good for your general well being. I am neither denying that some health problems are hard to diagnose and take many years but this isn't new to you. I wonder what you are going to gain out of pushing and pushing for something that may not be there.
There are numerous ways of managing, coping with and learning to live happily with health problems. It doesn't make them go away. It makes some days a little more bearable. Be kind to yourself and please don't take this as an attack on you. I'm sure you a lovely, kind and generous person and I know you are more than the total sum of any labels from doctors and any health problems. 