I wouldn't want to direct you either way but you do have genuine concerns! If you're seriously thinking of changing jobs I would personally do that first, get settled in a new job, maybe if you're happier at work you might then be able to find it easier to come off the anti depressants? Also with a 2 bed flat, if there's not room for two small children it could get very clostrophobic (sp) (not good for depression) and once a new bubba is coming moving and any DIY involved and the stress with a move will only be more difficult!
I know when you're broody it feels like nothing else matters and lets just go for it! Then reality sneeks into your mind! If you're not in a rush to have a second (age, health etc) I would personally wait until at least some of the doubts have been solved.
That's just my thinking, I have a similar situation and I'm forcing myself to wait a while. But it't totally up to you and OH what is best for you! x x