First, I want to say how much I admire your courage in bringing this issue forward. It must be very difficult for you to experience the symptoms and have a concern about their legitimacy and the diagnosis.
Your genuine struggle with this is one reason something like Munchausen Syndrome is not likely to apply, and your self-described ‘obsessive thoughts’ sound like where the bulk of the work is for you.
I am glad to hear you are in therapy and I would encourage you to talk more directly and deeply with your therapist
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral