Holding On To Imaan When Doubts Creep In

Assalamu Alaikum wa Rahmatullahi wa Barakatuh. I've been really struggling in my mind for the past few weeks, and these thoughts are becoming hard to ignore. I'm a Muslim by birth and by choice, alhamdulillah. I began taking my deen more seriously around age 21, after being diagnosed with a serious chronic illness. It was a wake-up call to reconnect with Allah SWT. Since then, I've tried my best to establish my salah and truly trust in His Qadr, believing everything happens for a reason, even if I can't see it. My life plans-my career, my studies-all changed after my diagnosis. I've learned to accept that maybe my plan wasn't the best one and have tried to follow the path Allah has written for me. Spiritually, I felt I was in a good place, especially the last few years. This past Ramadan was beautiful; even though my health didn't allow me to fast, I filled my days with Qur'an, dhikr, and sincere du'a. But lately, these awful, negative thoughts keep hitting me. I start questioning everything-is this all real? Is anyone truly watching over me? Is there really a divine plan? I feel immense guilt for even having these whispers, but my mind keeps dragging me back, feeling like it's undoing years of spiritual work. I'm not sure what I'm looking for by sharing this. Maybe just some reassurance or advice from anyone who's been there. I want to believe my du'as are heard and that things will get better, even if it's not in the way I pictured. I'm just so tired, mentally and spiritually, and it's starting to wear on my physical health too. My biggest fear is the thought of losing my faith completely. If you have any guidance or have felt similar, your words would mean a lot.