How much force does it take to break/fracture a nose or deviate my septum after rhinoplasty?

The nose reaches about 85% of its normal strength at eight weeks and is back to normal tensile strength at approximately one year. The force of the trauma should be about the same as if you never had a rhinoplasty. That being said it should be minimal if any damage from dropping a phone at that distance. 

Since your rhinoplasty was a year ago, I doubt that any damage was done to your nose from your phone hitting it.  During the first few weeks after a rhinoplasty, the nose is more fragile, but after a year everything should be well healed.  If it would make you feel better, you could always contact your surgeon and have him or her examine you.  

When the nose is broken, there may be nasal bleeding, and purple discoloration under one of both eyelids. Mild tenderness in the area will likely subside. Hope this helps. Dr Joseph