Coping with Death Anxiety and Growing in Faith

Assalamu alaikum. I'm a Muslim and lately I've been struggling with intense anxiety about death and what comes after. Every night, as I try to sleep, my mind is consumed by thoughts of the grave and the hereafter, keeping me awake till very late. I keep questioning: Are Jannah and Jahannam real? Does Allah truly exist? What if there is no afterlife and we simply cease to be? I don't feel like I'm leaving Islam, but my overthinking has become so severe that even casual mentions of death trigger panic. I also believe the hardships my family-my mother, father, and little brother-and I have endured have taken a toll on my mental health and shaken my iman, making me wonder if Allah is really there. Please don't be upset by my words; I just want this fear to go away and to strengthen my belief. I've looked into ways to overcome the fear of death, and some suggest living life to the fullest. But how can I do that when I lack the financial means and physical energy? I hope you can help me with rational advice.