Moved from Moths.
An adult to go with your immature stages:

This is Leucanthiza amphicarpeaefoliella (Gracillariidae). Its coloration and pattern of markings are indeed remarkably similar to those of Mompha terminella, although independently so, as the two moths belong to different superfamilies. The easiest way to differentiate them is the absence, in L. amphicarpeaefoliella, of tufts of raised scales on the forewing, as are prominently featured in M. terminella.