It sounds as though your GP was less than helpful with his comment about premature ovarian failure. From what I can gather, with my very limited knowledge, that sounds like a red herring - you say that you are able to trace your symptoms back over the last 2 years, which makes it sound like you've been going through perimenopause and are now moving towards being menopausal. Missed period, new symptoms - sounds like the next step towards menopause.
I can only say that I've no idea I am on that path - I haven't missed any periods, but I am getting the fatigue, insomnia, night time palpitations and adrenaline rushes, sweats, mood swings, blood sugar issues, spots, changing hair, skin and nails, changing cycle lengths etc.
Menopause seems to be one of those things that can only be said to have happened in hindsight, ie after 12 months without a period. Seemingly, until then, anything and everything goes, symptoms wise.