Toldos/Tolds/Tldos/Tlds

Over the last few weeks the word "toldos" appears in almost every parsha and is written in a few different ways. In Parshas Chayei Sarah, when discussing the generations of Yishmael, it is written Tlds, no vavs. In Parshas Toldos, when discussing Yaakov and Eisav it's written Tolds. First vav is there, the second isn't. In Parshas Vayishlach, when discussing the generations of Eisav, and in this week's parsha, Parshas Vayeshev, when telling us what happened to Yoseif, it is written Tldos. Second vav only, no first. Only in Parshas Breishis when discussing the heaven and earth is it written Toldos with both vavs. This made me think. Why the differences?
My thought was that shamayim and aretz were perfect, Hashem created them and they remained true to him for all eternity, therefore it had both vavs.
In the case of Parshas Toldos, I thought that being that Yitzchak was a tzadik, and even though Yaakov was, but being that Eisav wasn't, the first vav is there, but not the second, meaning that the present is there, but the future is incomplete.
By the generations of Eisav, the second vav is present because although Eisav was a rasha, he did have a navi that came from him, Ovadia, and therefore there is no present but some future, but Yishmael had no redeeming qualities, not he himself, nor in future generations, and for that reason he didn't merit either vav.
The Toldos in this week's parsha, relating to Yoseif is the one that threw me.....
Well, my Rav pointed me in the direction of a sefer called Kvoda Shel Torah. Lo and behold, I was pretty close.
He brings down that the Toldos in Breishis, relating to heaven and earth has both vavs because the letter vav represents life and when heaven and earth were created the malach hamaves did not yet exist and therefore that toldos is full. There is only one other place in tanach where toldos is written with both vavs. Can anybody guess where? OK, I'll tell you. At the end of Megillas Rus, when discussing the generations of Peretz the son of Yehudah it is written with both vavs, becuase there it is talking about the generations leading up to David Malka D'Mshicha and ultimately Tchiyas Hamaisim, hence both vavs.
The toldos by Noach (I had originally forgotten about that one) and the one in Parshas Toldos has the first vav because there was a perpetuation of torah values through those generations.
Eisav did not have the perpetuation of torah values, but at the end there will eventually be "V'Alu moshiim bhar tziyon lishpot es har eisav" which leads to the ultimate geula, similarly, the story with Yoseif, although it wasn't a good situation at the time, later on it became good, therefore it has the second vav, but not the first. Finally as I said with Yishmael, no redeeming qualities, no vavs.