You can always be unlucky when it comes to injuries, even if your case seems to be extremely unlucky... I've also seen teams going into the playoffs having their 3 top-players injured, so impossible is nothing :-)
Arena: The estimation that you see is almost never the real time needed to finish the expansion. It's rather a best-possible-case. It's normal that it takes several days longer.
We have both said a lot of things that you are going to regret.