Ok tried Literata Book, sadly it didn't really get me anything. Yes at the *same* settings it would give me more lines/page, but I needed to adjust it to 1) make it comfortable to read 2) get rid of artifacts from the first line of the next page showing at up the bottom of the current page.
However, I had an idea sparked from looking at these two fonts, I decided to look at Bookerly's line spacing and discovered that (based on what I've read) the ascenders and descenders were incorrectly set, resulting in (I believe) a larger space between lines.
This is based on information from this site
http://designwithfontforge.com/en-US/Line_Spacing.html I've since corrected the values and I do find that Bookerly now seems to have a smaller amount of space between lines. Which makes sense based on the adjustments I made as the values that were edited were all decreased. I will admit that this is not an area where I have a great knowledge, so perhaps I'm mistaken in my evaluation of the information. But the net result is I now have a Bookerly font which gives me more lines per page than the one that Amazon distribtues and presumably uses on their Kindles.
As to why Amazon would not follow this supposed standard I can't say, perhaps they felt it looked better, or perhaps Kindles take the difference into consideration when rendering text. Note I'm honestly not trying to assign any nefarious mentality to Amazaon I'm just reporting what I have found and speculating as to why they would do this.