The ability of making a note sharp or flat allows subtle changes that I appreciate. I have found the the higher the note, the more difficult it is to “Bend”. Is this my playing or a universal truth?
Seems to be the case for me, but there are other factors. ‘Throat tones’ like B, C, C#, are pretty flexible (keyed C more than cross fingered). Also, 3rd octave notes don’t want to budge.
My cylindrical flutes (PVC, Hammy) are more flexible in the low octave than my old dead german, Dulcet, or Boosey. Embouchure cut makes a difference, I suspect.
As is usually the case, the skill of the player is a huge factor. I’m sure that a good player could pick up any of my flutes, bend any note, and probably play in tune, too 
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Could be the flute, or it could be that you are not allowing for enough control in the second octave. As each flute will play differently, you will discover that they each require a different approach. Some need to have the embrouchure nearly down to a very fine line to bend the note, whilst others need only the slightest alteration, and a little less force on the blowing aspect. If you get what I mean? 
Oh yes I also forgot: some older flute players (myself included) will often roll the flute when trying to get the note. After a while you realise that your mouth automatically can find the right spot to bend the note successfully. Cleachtadh, cleachtadh, cleachtadh!!
(practise!) 