Red, I think you're right that you're getting stronger. It is really good to see you appreciate that and to see how proud you are of what you're able to achieve. Leaving in the first place and starting to talk to the therapist both took a lot of strength. You should be proud.
With respect, though, I think you're letting your (totally understandable!) happiness about this strength cloud your eyes to seeing something else important: you're not strong enough to change his behaviour. And you can't be, nobody ever could be, because the only person who can do that is... him.
So you're proud of yourself for telling him not to roll up or smoke in front of DD - and he did what you said! That clearly is not a conversation you could have had with him before, and you've come a long way in being able to have it. But meanwhile, surely what you want is for him to not want to smoke in front of DD? For him to choose not to, all by himself, without you needing to monitor him?
It must have taken a lot for you to tell him that you want him to go to therapy, and to keep telling him as he wriggles out of it. But you know (and I'm sure your therapist would agree) that even if you could drag him there kicking and screaming, that would not be any use at all, because therapy is only going to help him if he wants to be there and wants to engage. Not because you've made it easy for him, but because he himself wants to change. You can't do that for him.
You're proud of yourself that you can see through and call him on more of his bullshit now: you realise that his excuse for still using is an excuse, you realise he's avoiding therapy. It's great that you're strong enough to see through him on that! But where's the next step, for you? You say "you need to do this", he makes excuses and doesn't, you realise it's excuses and then... you ask him to move in anyway.
You getting stronger is a great thing for you, and for your DD, and it has the power to change both your lives so much for the better. Not just for a couple of months, but permanently. But no matter how strong you get, you can't make him make different choices. So you need to look really, really hard at the choices he is making. Not just the ones you like seeing, but the ones you don't.
I know it is scary to take that step back. When you've spent so long trying to manage his choices and his moods and his life, it's hard to go "well, I'm going to tell you what I need you to do, and then it's up to you to step up or not" - and then make your own choices based on what he's doing, not what you want him to be doing. But you have done so many scary things. You can do this one, too, you really really can.