Can Our Du'as Truly Change Our Qadr?

Salam everyone. Honestly, I’ve just felt so down and hopeless for a bit now. I’ve been making du'a constantly, but it seems like nothing in my situation is shifting. It’s left me feeling kind of lost and unsure. So I really need to ask: can our sincere du'as actually alter what Allah has decreed? If you have a moment, could you share a story of a du'a being accepted? Just to be clear, my Iman in du'a is still there, alhamdulillah. A small example: before Ramadan, I begged Allah for a Ramadan without migraines, and by His mercy, I didn’t experience a single one throughout the entire month. I know and believe He answers. I’m just overwhelmed with a deep sadness right now, and hearing from others would really strengthen my heart.