I am missing here information about your Education level.
When I did simulation with this and using Master for education, but no points from spouse (as you did not specify, that you have her ECA or language test, I ended up on 420 for you as married.
Furthermore, in your case the points difference for better IELS results will be much less significant. The way you are, you have already achieved 100 points for transferability. So better IELTS will bring you 10 to 20 points max (of course under condition that you do score better).
So that alone tells you, that you need your spouse ECA and language test.
What I do not understand is the reason of not being able to take 1 day test because she has child. Sorry, but if you want to immigrate, you will surely find a solution for that (for example you will take a day off in your work and take care of the child, while your wife will go to do the language test).
best luck there.
