I honestly don't macro anything to NS anymore due to this issue, as I use NS in the middle of a normal GCD (since it's off the GCD) followed by the spell I'm using when the GCD clears. Too many times I've shifted out of form when doing this, rather be safe than sorry.
problem is, the server first needs to know if oyu have the buff before it will let oyu cast it without shfiting out of form
this takes a few millisecs but this makes it unable to put it in 1 macro
you try to use some of the examples above, however i persnoaly have /cast Nature's Swiftness macroéd to all my attack so i always have the buff up thne i just got to click HT or Rebirth whne i think the time is right