No, I don't imagine it's caused permanent problems, but I'm not in a position to say. In my mind I see it as similar to a bad park in the car. If you don't reverse at the right angle and speed, it doesn't matter how many times you shunt backwards and forwards, sometimes your only real option is to get out of the space, and start again! It would be interesting, with your GPs knowledge, to try a quarter tablet, to see if the worst of your symptoms abate. If they do, then maybe you need to keep that going and then start decreasing extremely slowly.
If it doesn't seem to have any impact, or makes you feel even worse, then you know it's your current state, and not the medicine.
The "it's fine to stop cold turkey" is reckless, and typical of those who know what they've read, but not experienced it themselves.
I do think, though, that you are blaming your GP unfairly. He prescribed it in good faith, if anything, it's one of the best tolerated of the anti-depressants.
He must've chosen this particular one for a reason. It's usually given when the patient has a problem with insomnia as well as depression.
So, did you already have insomnia before you took it? I thought the insomnia was a result of taking the medicine.
Some drugs have suited me better taken first thing, others at night. Some I've taken as much as is possible, some I've only needed the lowest dose.
Usually a gp will suggest a prescription if the person in front of them seems to be really struggling. If they're just beginning to feel a bit overwhelmed, then maybe they'd suggest some of the cbt materials that are available in the NHS, but normally people only present when they're close to wits end, in which case, a suitable antidepressant, and being put on a wait list for therapy would be the ideal combination for most people. In the current climate he probably concerned about patients getting worse and not being able to deal with that later, and is erring on the side of caution.
A GP is very unlikely to suggest "natural remedies" because their potency is not regulated, there are often lots of side effects that have not been properly catalogued, and again, if he thought you were struggling he probably didn't want to mess around. A good example would be "mindfulness". Supposed to be the answer to everyone's woes, when actually, if you're really depressed, it can be quite scary. It helps millions of people, but there are definitely people who shouldn't! Natural means nothing when it comes to supplements. We had 2 cases at the end of last year of young adults ending up in A&E with 2 different organs failing because they had been given "natural remedies" by naturopaths, and one of them ended up in a transplant list. If you don't know what you're dealing with, it can be as disastrous as orthodox medicine.
Choosing an antidepressant is like choosing a friend. You don't just make friends with the first human you see, because they're female, same age as you, and work in a similar place. Not every drug is going to be the right one first time.
I think, given that you end up in despair so many nights, you may benefit from asking for help trying something else.
I understand your reluctance, I really do, but sometimes it's difficult to see the woods for the trees when you're right in the middle of it.
Are you now waiting for counselling or therapy? There's a huge amount they can do for anxiety now with different techniques, maybe explore that too.
Hope your managed to get some more sleep. 