It takes a lot of patience to raise a kid without spanking, but I believe that the results are worth the extra effort.
If she is genuinely strong-willed, good luck. You are still at the beginning of this particular road. Watch out for tight curves ahead.
Some of us have guided children all the way through the road to adulthood. Many of us also said, "I will never have to spank this child," and discovered otherwise. Others have said, "I will never spank this strong-willed child; there are better ways," and now regret the vow.
But you may beat the odds. Good luck.