The writer uses the word "For" to begin explaining why he is confused and asking God why he is not coming to help. (See: [[rc://en/ta/man/translate/figs-explicit]])
This means that he has been trusting in Yahweh since he was very young. AT: "even from the time that I drank milk from my mother's breasts" (See: [[rc://en/ta/man/translate/figs-idiom]])
The phrase "have been thrown on" is a way of saying that Yahweh has taken care of him as if Yahweh had adopted him as his own child. This can be stated in active form. AT: "It was as though you had adopted me right when I was born" (See: [[rc://en/ta/man/translate/figs-idiom]] and [[rc://en/ta/man/translate/figs-activepassive]])