I cant really say that I have this "phobia" per say. However, I have disease called Multiple System Atrophy which doctors say the chances of living past 6 years is very slim. So, I do often think of my death, but I dont dwell on it as each day to me is precious to live no matter how much pain I may have. The questions that you are asking there is no way that we as mere mortals can answer. I am sure that you know this. I am glad that you have decided to seek another physicians advice. Please keep us updated.
I am not sure that I can help much with this one. I dont so much worry about the big questions like you, but I do worry ALOT about dying. I was recently DX'd with fibro, and worry way too much about whether I really have some serious disease that will kill me. It too at one point consumed my whole life, I worried from the time I woke up til I went to sleep, then many nights would have nightmares about it. Its scary and consuming. My only advice to you is talk to your doc about it and try everything available to you until you get the help you need. Please hang in there even though I know how hard it is.