I am so sorry to hear how your fears are affecting your life. I have another therapy for you to try that you may not have heard of - it's called EMDR - Eye Movement Desensitisation and Re-Processing. It is a trauma therapy that is recommended by the National Institute of Clinical Excellence in England and is used all over the world. It originates from the US by Francine Shapiro and it is recommended for panic attacks and unexplained anxiety and it's various symptoms. You have described suffering from various things in your email and that includes a cyst on your brain - you would have to mention these things to your EMDR therapist for them to check out whether they are willing to treat you with these conditions - I would still believe it is worth pursuing this.
EMDR is based on the theory that your panic attacks are an experience of emotions that are held in your subconscious mind, from many years ago (in your case, prior to being 13). You do not need to know what the incident(s) are that may have caused your symptoms in order for EMDR to be successful, because the therapy takes place in your subconscious mind where the details are held. No therapy can change your past, but EMDR can process away the emotions that are being carried, and are currently being triggered in your daily life. Again, you may or may not be aware of what these triggers are, and that's fine.
The therapy uses a bilateral stimulation of the brain (often using eye movements, lights, tapping, or gentle electrical pulses on the palms) and this simulates the processing away of anxiety that normally occurs in REM (Rapid Eye Movement) sleep at night. Some information in your subconscious mind is causing this distress and you do not need to live with this distress forever - you can live perfectly well without this it.
The doctors have checked you over and found no physical reason for these panic attacks - I would recommend that you search the internet for a local EMDR therapist. Try www.EMDR.com for more information and a therapist who you like the sound of.
I wish you the very best with this, Sarah