I think too often we say "God is all I need", but then when we get to a deep and dark place in our lives, we despair and it becomes apparent they were simply words we said.
"LORD, you alone are my portion and my cup; you make my lot secure." (Psalm 16:5) David knew God was all he needed. Not only that, but David knew that if he had God, everything else in his life would be "secure". Actually, God promises just that, "And my God will meet all your needs according to the riches of his glory in Christ Jesus." (Philippians 4:19) It seems at times though, as we encounter difficulty in our lives, we think that "we" need to fix it. That we NEED whatever it is in our lives that now may be absent. Maybe it's money, a close friend, or even a spouse. Instead of "elevating" that need above God, take a deep breath and remember that God is all you TRULY need.
Instead of wallowing in despair or self pity, turn it over to God as He's commanded. "Cast your cares on the LORD and he will sustain you; he will never let the righteous be shaken." (Psalms 55:22) and "Give all your worries and cares to God, for he cares about you." (1 Peter 5:7) Then wait, "Wait patiently for the LORD. Be brave and courageous. Yes, wait patiently for the LORD." (Psalm 27:14) Remember, this difficulty is happening for a reason. You don't need to understand "why", but you do need to accept it as it's God's will for you right then, "give thanks in all circumstances; for this is God's will for you in Christ Jesus." 1 Thessalonians 5:18
What can you do if you are still struggling in the midst of the storm? Keep seeking God's face. "I keep my eyes always on the LORD. With him at my right hand, I will not be shaken." (Psalm 16:8) God is always faithful, so know that He is working out what is best for you. It may not resolve how "you" want it to, but trust that God knows what's best. And even though you may "feel" shaken during these struggles, keep the faith. As, "without faith it is impossible to please God, because anyone who comes to him must believe that he exists and that he rewards those who earnestly seek him." (Hebrews 11:6) Lastly, trust in God's promises and words to you during these times, "For no word from God will ever fail." (Luke 1:37)
God loves you. God will never abandon you. God is always faithful to those who love Him. God will provide all your needs. God will support you at all times. God sent His only son to die for the forgiveness of your sins, and to provide you a pathway to eternal life with Him in heaven one day.
Do you really need anything more than that?