LOL, I am responding to your "what happened":
I too breast fed both of mine as long as my body could with working (just over 5 months with my second) and had some frozen breastmilk that I would mix with formula/cereal, etc. However, one day I absentmindedly stirred the cereal and put the spoon in my mouth and YUCK! It tasted horrible. It was a mix of dinner foods and slightly sour tasting. I know it wasn't bad because I would put them in the fridge to cool, then right to the freezer after pumping. It was right then I decided to dump the pumped milk and go right with just formula.
I didn't read your other responses, but I don't think there is a formula that tastes like BM because it takes on the taste of the foods you eat to acclimate them to different flavors.
Soy formula tastes much different though than regular formula.