Begonia aff. mildbraedii

I received this plant about 8 years ago, and have since lost any information on it.  It slightly resembles Begonia mildbraedii, but looks like a different species to me.  The largest it has gotten for me is about 4? tall with leaves around 2? wide.  It has red stems and leaves that range from a pale red (grown in high/too much light) to a slightly glaucous green.  It’s not flowered yet.  So far, it has been a slightly finicky plant, doing well for a time and then melting away, over and over.

The second image is of a particularly purple plant, (no edits were done to the photo).  I’ve never seen it this color, but think it is a response to osmocote slow-release fertilizer that it was fed recently.