Goats will lose two teeth every year, the middle two their first year the next two the next year, etc until they are 4 (they only have 8 teeth on the bottom). This is one way to tell age in a goat, after 4 years you just guess by how much wear the teeth have or if any are missing. Your doe should lose one more tooth in front and have two big ones come in.
One another note, I have yet to find any goat teeth. I have horse teeth and camel teeth in my collection, but no goat teeth.