From your post it sounds like one of the options is for her to buy her own place. That seems like a really healthy and positive solution. You give space to the children to blend/merge with shared experiences (sharing dinner and adventures, etc.) while allowing them the familiar comfort of returning to their "own" homes. Your lady gets to have the safety and confidence of moving toward owning her own home, while still not combining finances with you in a "make it or break it" urgency.
Then, if her recovery stays on track and a year from now you want to deepen the commitment, you could always rent her place out and all move in together.
You are showing love and commitment in the "moving towards" living together, but also in encouraging her to make an independent financial decision which will be a safety for her and give the kids the opportunity to come together as a family in stages.
My experience is that when things start feeling "now or never" urgency, something is wrong.