Hmm how many? All of them. But one particular act may extend along multiple volumes.
For example, Fire's current story, "Act I" is everything from the beginning to the point where she's with the Uranians and realizes she's going to have to go on this mission. So that's currently all of Book 1 and half of Book 2.
Within this "Act I" and several smaller Act I-II-III groupings. such as "Begin Auction - Secure bee - Escape Auction"
Q: Too long?
This is hard to answer, but I can definitely say I don't feel the length of a book, but rather the strength of the reward for reading the ending. In this sense, Han Solo vs Kylo Ren ending left me unsatisfied. Unrewarded. And one may make a counter-point that sometimes life is random like that, and not every death has meaning, but I would argue this should have meant more and rewarded more. It wasn't far from the death of Superman or Optimus Prime, (both of which the companies chose to walk back but Disney decided to plough forward).
If the reward is great enough, no length is really too much.
consider to be the end of act one/beginning of act two
I have trouble dividing the acts unless I reach the end.
(I imagine you face the same dilemma if you tried to split Laurie's journey in the ship right now. You know she goes to town on the crew in the third act, but where exactly did Act I end and give way to Act II? I checked my notes. Formally, Act II starts in chapter 20 when Laurie commits on a course of action. A purist would say her first commit is much earlier, probably around the introduction of Alice where the journey-story changes direction to survival-story)
For yours, I can guess Act I culminates the destruction of Joseph's homeworld, but not knowing now much story comes after that, I could be way off.
My concept of "too long" is really how many disparate elements I need to track over how long a period. As long as there is character growth, I'm usually along for the ride.