I've never given soymilk to my children even before I knew of soys estrogenic compounds. The reason being that in TCM soymilk is a very cold natured food, one that is difficult to digest and could lead to deep coldness and deficiency in the body. Most women I see that complain of vaginal itching are linked to drinking soymilk as well. When the soymilk stops, so does their itching.
In rural Japan some of my friends are from, I'm told tofu is not eaten more than once a week, because they say it leads to bad digestion.
Don't forget that tofu is the diet of Sumo wrestlers as well, it causes them to bloat. More evidence of the antithyroid connection.
As an alternative to soymilk or any boxed milk out there, fresh made almond milk is a delicious drink. I've made it for many years and never tire of it's wonderful freash taste that a boxed milk lacks. It's enzymatically active as well, since it's raw.