I thought it was Kushina who was modeled after his wife? He said that. Kushina, who is like Sakura. So I guess the only thing he likes about his wife is her boobs.
I said recently in another post the girls in the manga have more in common with Sakura in personality than hinata, which to me mean he got a type. So for me it doesn't matter if he was dating his wife before he started writing Naruto or not. He clearly got fell for his wife because she was his type and started modeling sakura a bit more after her, and made kushina on her recommendation.