When I use to have long, complicated dreams like that, often it was "duplicates" of a message. Your dream reminded me of that when you got in the old car and couldn't see out the windshield, that reminded me of the truck in the beginning and the confusing landscape. Too, the truck fell into the ocean and you couldn't see over the dash of the car and rear-ended a red truck.

There were a couple sets of "parents" in the dream too, first you were one/with friends and their daughter and then your mother was digging asphalt for a garden was sort of like your two or three changing landscapes; the tundra to green to snow at the begining, etc.

A third "pair" of things was the idea of crazy; first you were trying to get your son back and then the nutso lady trying to get her own son back (that's a pair of pairs, LOL).

Were it my dream I would look at those various themes and think about "then" versus "now" or whatever, see if you can see something happening or being thought about or discussed in your life/therapy that has happened before. Allegedly we're every character in our dreams and that last pair of pairs where you were crazy looking for your son (a younger part of you?) versus the crazy lady going on about looking for her own son, right after your mother said mean things to you. . . that would really interest me if it were my dream.