Ok, let me recap this:
You bought a phone, then after that you started to think about if it was right and discuss troubles you might have in various threads. Then at last you have the phone in your hands and worry a bit more about what problems and glitches it might or could have.
Have I outlined this right?
So what exactly do you expect from us? Shall we ease your ongoing sorrows? Shall we affirm them? Because I have yet to hear one single real problem you have with the phone, so I would in all earnesty assume that any problems at the moment are more due to nervousness and a troubled mind, than to anything physically notifyable.
On the other hand, we are just smartphone geeks here and mostly not therapists of any kind.
Therefore all the help you will get here is with real troubles you have with your Nexus 5.
As for the worries that plague you, I think you have to appease them yourself, because noone can help you from "fearing" or "expecting" bad things.
Ok?