In charge

So my mediocre life as an EMT has included a handful of calls where I acted as the "in charge" person - all BLS calls, all leading EMT's and First Responders.
All of that has begun to change.  Mr. Medic is throwing me at patients.  And I'm failing. 
He served an apprenticeship under his mentor in a large city system.  Even after his stint in paramedic school, I think they made their medics ride with a preceptor for another year.  That was standard for their system at that time.
We don't have anything nearly as official in place here, but Mr. Medic seems intent on grooming me for my new role as paramedic.  In a year's time I will be expected to take care of people and it's time to step up my game.
Haven't killed anyone yet, but focusing on the fact that the guy has a 20+ year history of migraines and neglecting to check for stroke...oops.  Talking insanely loud because you are nervous...oops.  Spiking an IV slow as molasses...  Seems like every call I go on I forget things.  Just taking a good history (at which I thought I was decent) has turned into a bit of a nightmare. 
I have a good rapport with Mr. Medic but I don't want to disappoint.  I want to be perfect.