God said to Moses, "I AM WHO I AM." And he said, "Say this to the people of Israel, 'I AM has sent me to you.'" (Exodus 3:14 ESV)
"God has in himself all power to defend you, all wisdom to direct you, all mercy to pardon you, all grace to enrich you, all righteousness to clothe you, all goodness to supply you, and all happiness to crown you." (Thomas Brooks)
God's covenant name in the OT is based upon God's description of himself: "I am." He means more than he is the self-existent One. He is that. He is totally independent and self-sufficient. But he is more: his being the "I am" in the Exodus (like Jesus repeated in the gospels, "I am...") means that he will be all that his people need him to be. He is not only wholly sufficient in himself, but he will be wholly sufficient for all those who trust him.
(The photo above is taken from the summit of Jebel Musa, the traditional site of Mount Sinai, along with the Tetragrammaton [YHWH] in Hebrew.)