Hi ellie, I don't have any amazingly-helpful words of wisdom but I just wanted to say that I empathise, and you're not alone. I have struggled with clinical depression since my teens...I came off medication a year ago and can honestly say it's been the worst year of my life. Thing is, I came off them to start TTC...and now I'm 5 weeks pg and terrified.
My decision to come off Citalopram was entirely personal (and heavily influenced by the fact I'd been on it for ten years), so I would totally echo Marquand - I spoke at length to my GP about being on Citalopram and being preggers, and he also said that a depressed expectant woman is a lot worse than a dosed-up one! (Or words to that effect...!)
It sounds like you have a bit of 'system-fatigue', which I also empathise with. I'm not sure what else anyone can do for me. I flagged it with a different GP on Friday, and she just looked perplexed! I started a new course of CBT last week but the therapist was truly awful, so I've stopped that. I'm going to investigate private counselling, and maybe support groups....my biggest 'trigger' is feeling alone. Seeing lots of other depressed people would really cheer me up! 
My DH is an absolute sweetheart but doesn't cope when I'm ill. I'm struggling at the moment because I want to be excited about our news, but his preference is to pretend it's not happening until we're certain everything's okay. I understand this, but the silence isn't helpful when you're prone to too much introspection!
I wish you the very best of luck. I'm sure there are lots of us in the same boat so maybe this thread could be a bit of a support?