Is it okay to say "my latest five novels" when I want to express "five of my latest novels"?
As far as I know, "five" is a postdeterminer, so it precedes an adjective (except for "last/following/top", to name a few) as a rule.
This usage depends on your desired emphasis. Either grammar is acceptable. Your choice depends on whether you want to emphasize "five" or "latest," or "novels." In classical grammar "five" would be deterministic but any order is acceptable in modern usage depending on your intended meaning. A warning: Depending on context your choice of emphasis may slightly alter the perceived meaning of your statement!
This means the last five novels that you have written: no more and no less.
This means that you are referring to five particular (but unspecified) novels selected from an unspecified number of your recent novels. This has the implications that:
Finally, both expressions also carry the implication that you have published 'substantially more' than five novels in total, e.g. at least ten (but that number is for the reader to guess at).
Latest is usually used to say "the most recent" or "the newest" as in:
To use a number greater than two with latest such as their latest five CDs or five of their latest CDs seems to contradict that meaning of "most recent" and "newest" although both grammatically correct.
In my opinion, I would use the adjective, last, which is commonly used to talk about a period of time up to the present but can also be used to talk about a series of things made, released, published or performed up to the present day for example:
(I have no idea if this last statement is factually correct. I am merely giving an example, apologies to Mr Cruise!)