I'd talk to the Dr. and get a suggestion. I know my friend's kids love soy milk. There's also rice milk and almond milk. You can usually find all of them at the supermarket.
Hi there, I am sure that you have probably already got to your solution by this date, but if you are still looking, I had to wean all four of my kids around a year of age. And none, of them liked formula and I wasn't ready to give them whole milk. So I went in between I used lactose free formula and then transitioned to lactose free milk. Now all of my kids love soymilk. Hoping you are finding what fits best for him