Considering how short a time ago you broke the leg- I am surprised you are even able to ride yet.

If I was you- I'd do the ride in reverse next time- Then you won't have to wear out your shoe leather by walking this hill.

But what a target to aim for- 1/2 mile at 15% in any gear will do within the next 6 months.

( And the local basket at 16% I don't do very often- I have to be fit and I have to be in the mood for some slow cadence work.)