Omg123, in some ways it's almost easier once you have accepted that it is a long haul.
A few years ago I would have said what you said about affecting the whole future. Now I am not to sure.
Yes, dd has missed a lot of school and she will have slightly fewer GCSE's, but she will still be able to do the same A-levels as she would otherwise have done, and I would have thought it very unlikely that a university will care if she has a slightly less brilliant GCSE record seeing that she has a genuine reason. (I work at a university myself and we don't discriminate against students for MH issues past or present; quite to the contrary, our SN support is a very big part of what we do.)
Dd's friend has been HE'd because of SN but is now doing his GCSE's and will then go to college for A-levels. Other HE'd children go straight to university.
Your dd doesn't have one chance to do well educationally and then that's it. There are plenty of ways of getting back into the educational system, all sorts of ways over and under and around.
Most people hit a bad patch at some time in life, and most people eventually right themselves and go on. Very few people find a bad patch closes all doors forever.
My dd's situation is slightly complicated in that she also has a chronic pain condition which sometimes affects her mobility; she is doing quite well now but is on permanent painkillers; before she started those she spent a lot of time in a wheelchair. This condition is one she was born with, but the symptoms sometimes ease or disappear with age (and sometimes worsen).
As to her anxiety/depression, CAHMS have told her that it is likely she will always have a tendency to react in a certain way to stress but that she can learn to control her reactions. Her therapy is very much about developing control mechanisms and to have a plan for when things go pear shaped.
The treatment plan is that she will see her therapist less and less over the next few months and then only for occasional review meetings. I don't think they expect her to stay on AD's for the rest of her life but maybe for the next year or two.
As to her suicidal tendencies, I don't feel she actually wants to die or finds life worthless. I think of it more as risky, impulsive behaviour, as if she was experimenting with drugs or picking up strange men in bars. It's shit because it can so easily go wrong. But if it doesn't go wrong, if she can only keep alive for the next few years, then I don't think it's her whole life ruined.