Yes, something's not completely right with the uniforms/ranks. I've considered you're suggestion, but I want to keep the midshipmen with the unifoms used, because they're jackets look rather lowest-rank. But I think I'll give the 2nd lieutenants a 1-rank promotion, and the 1st lieutenants a 1-rank degradation 
That would work too, as long as you removed the feather from the current 1st lieutenant's tricorne and perhaps changed his neckware to something less formal.
