I didnt consume collagen product drink directly but I consume products that enhance and boost the collagen production in our body. I dont think it will affect your breast milk.
BTW, consuming collagen drinks directly will not boost your inner body collagen as these collagen drinks will be broken down when they reach your stomach. Therefore, better if you consume products or foods that boost your body production of collagen as that will be store in your body.
I consume this brand that boost the collagen production and it has a rich source of anti-oxidant that enhance the cells to rejuvenate etc. Interested please PM me.