Strengthening my trust in Allah’s plan

Assalamu alaikum, everyone. I recently came back to pure tawheed and the real Islam, and alhamdulillah, I feel closer to Allah than before and believe He guided me here. But lately, life has hit me with so many tests that I can’t see a way out. I’ve lost someone dear, and there are problems I just can’t fix, which leaves me feeling broken and hopeless. I tell myself to trust Allah’s plan and let go of what’s beyond my strength, because I know I’m too weak on my own. Yet, my heart is still tied to the person I lost, and the sadness over these unsolved struggles won’t fade. I know we’re supposed to put in effort if we want something, but these things are completely out of my hands, and I don’t even know where to begin. So how do I really trust Allah? I want to have yaqeen in His plan, but why can’t I rely on Him fully? How can I shift my mindset and grow my imaan? JazakAllah khair for any advice.