First, the guy that left AMA you cant do anything about, he obviously didn't give you time to think about it. If you had remembered after he left sometimes homecare will go out and remove them.
Blood cultures sometimes get contaminated, that is a normal mistake you have learned from it and probably wont make it again.
I am not clear on the sedation part, so what I will say, we have a read back policy, when a doc gives you an order you read it back, it then say yes or no when you sign the order you sign it T.O. Read back N.Nurse RN/Dr. Smiley
Hope this helps, it takes at least a year to be comfortable in any position in nursing and sometimes longer depending on the specialites. Dont' sweat over them, they are learning opprotunities