I doubt this highly. Searching for the name, I found little evidence that is a widely used Russian name, and if used, is probably borrowed from outside, by parents with some reason to want to use a less-Russian name. I also have a British friend who spent a lot of time in Russia, a Lauren, and they had huge difficulties with her name. Because she made concessions, a lot of her non-Anglophone Russian friends now adamantly call her Lara. Never once have I heard her be called, on purpose or by accident, Lorena. She's been called Lara, Lora, even sometimes Larisa... never, ever Lorena. If this was a known Russian name, don't you think that -somewhere- Lorena would have cropped up?
Loren'ka sounds extremely strange, possibly because all evidence suggests that Lorena is not a Russian name, but also in the way it is formed. It -is- logical, in a strange fashion, but it -does- sound weird. Also diminutives which you're basing your question on, such as Sashen'ka and Mashen'ka are very intimate and affectionate, so rarely used socially, and are not formed with the –ka suffix with every single name out there. If I had to create a diminutive, based on its similarity to Lauren, whose diminutives were in turn based on the very Russian name Larisa, I would say the most common acceptable diminutive would be Lora or even Lara.
As I've said before, this is a guess. Lorena is almost definitely not a name used to any extent in the native ethnic Russian population.