First, let me clarify a couple things. Yahweh is an incorrect transliteration. It most likely was the result of a convenient, yet ignorant modification for better ease of use. Such translation lacks basic knowledge of the Hebrew language.
Secondly, YHWH is also incorrect. Hebrew does not have a letter (W). However, when the (W) sound is translated into Hebrew, it is depicted as [(Vav-Vav) (ו ו)]. Since the actual Hebrew tetragram is: [(Yud-Hey-Vav-Hey) (יהוה)]...with only one [(Vav) (ו)]...the corresponding Latin characters would be written as YHVH.
That said...the exact pronunciation of (יהוה) has been lost because the Hebrew alphabet does not contain specific vowels and the present Masoretic vowels are not genuine, as they appeared only after 500 CE. Before this epoch, the only vowels were the matres lectionis.
Despite this, the pronunciation is not completely lost. Like any language there are certain rules regarding pronunciation—like (knight) is pronounced as (nite). So in comparing the Qumran’s writing of the first century, YHVH would most likely be, Yehovah or Yahovah.
The discrepancy results because the first two letters, [(Yud-Hey) (יה)] are pronounced both ways. I’m sure there’s a more factual basis for the adoption of Yehovah, but some believe it was chosen to avoid an eventual blasphemous misinterpretation of the expression.
You see, (Ya) is the short name of God, as in Halleluya or praise Ya. And (hovah) means disaster. So in Hebrew, since the words (is) and (a) are incorporated into the words that precede or follow them—Ya-hovah may be interpreted as (Ya is a disaster).
For you, it would be best to write YHVH and to say Yehovah...
But this is only my opinion...
As far as YHVH meaning...
"I am who I am"
This is a falacy...
The verse from Exodus 3:14
eheye asher eheye = אהיה אשר אהיה
Literally means...
"I will be whatever I will be"...