Oh yes, I totally understand the struggle, I went through the same thing when I was trying to boost my supply and wanted to bake my own lactation cookies from scratch! I actually managed to find both ground flaxseed and brewer's yeast at Phoon Huat, which carries baking ingredients and is pretty accessible if you have a branch near you. A mum friend of mine also mentioned she picked hers up from Cold Storage or FairPrice's health food section, though availability can vary by outlet, so it's worth calling ahead. For the recipe itself, the classic combo is rolled oats, brewer's yeast, ground flaxseed, butter, eggs, chocolate chips, and a touch of brown sugar, just bake at around 180°C for 10 to 12 minutes and they turn out really well. Some mums swear the brewer's yeast makes a noticeable difference, though a few did mention the taste takes a little getting used to, so starting with a smaller amount in the recipe is not a bad idea. Hope this helps, and wishing you a smooth breastfeeding journey, you're doing great!