God did not follow through again

Wait a minute.  My last post is Gen 13:16 which says Abram has as many seeds as the earth has dust.  Why then does he have no seeds later?  Gen 15:2 says, “ And Abram said, LORD God, what wilt thou give me, seeing I go childless, and the steward of my house is this Eliezer of Damascus?

15:3 And Abram said, Behold, to me thou hast given no seed: and, lo, one born in my house is mine heir.”  Now don’t tell me that it is because he hasn’t had time.  He founded a new home after walk through the land in the length of it and in the breadth of it (Gen 13:17.) and fought a war to free Lot.  How much time did a man with a worlds worth of seed need to have a kid?