Just read whole thread. I think 20mg was a bit high as a starting dose, 10mg od would have been better I think. Out of interest, had you been taking valium regularly and then stopped when you started the citalopram
If you are referring to valium as lovely (the feeling it gives you is lovely, I'm sure) and wishing you could stay on it indefinitely, then in the nicest possible way, I think you need a reality check. Valium is highly addictive and masks your anxiety whilst giving you another problem to deal with - that of increasing tolerance and dependance over time. SSRIs, whilst having varying degrees of nasty side effects and difficulties in coming off them, don't have the same issues with tolerance and needing larger doses. It works well as a short term measure, but there's a reason you can't keep taking it and it isn't just to stop you feeling lovely.
Regarding citalopram, I've been on it for about 8 years now. It's had the best, most stabilising effect of all the ADs that I've taken (venlafaxine, on the other hand, was absolutely fucking disasterous for me and my life, and made me briefly suicidal and manic). However I've always been able to reduce my dose in the summer when I'm more stable, and increase it in the winter. The last two years I've found that harder and this year I've had a real bugger of a time reducing it this summer, despite being in a better headspace than previously. If I miss just one dose I start getting brain shivers and feeling very odd, which absolutely did not happen previously. I've had to reduce incredibly gradually, reducing by 5mg every other day (so cutting 10mg tablets in half and taking 40mg one day and then 35mg the next, then 40mg, then next day 35mg again, then every two days until I'm stable on 35mg each day Then I've done the same down to 30mg per day). This has never happened before - I've been able to reduce by 10mg at a time - but this time I've been fine, reduced the dose and just crashed a week later. It's put the wind up me a bit and I want to try coming off them.
Anyway sorry for rambling on. My point is that it takes trial and error to find an AD that suits you, so you're right not to put up with unacceptable side effects. Keep with it though - when you find the right one then you will feel better, promise. 