That function returns the last message created, but if you created it, you already know its position 
Maybe I explained myself badly but I remember that in this post I gave you two options,
which one did you use?
Also use fictitious names, I’m only interested in seeing how deep you go into the subnodes.
If you follow the example I gave you in this post, you can easily use a list and use ‘add item to list’ (you don’t even need to number the messages when sending them to Firebase because by sending a list, they already have the key that corresponds to their index in the list).