Am I Being Punished? Why Aren't My Duas for My Mom's Cancer Answered?

Assalamu alaykum everyone, My mom was diagnosed with stage 3 cancer a year ago. Since then, my relationship with Allah has changed a lot. I pray, I pray tahajjud, and I ask others to make dua for my mom. But none of these duas seem to be answered. It's been a whole year. Six months after that first diagnosis, we got another cancer diagnosis-stage 1 colon, completely different. After that second one, I was shattered, but I thought Allah is testing me and I just need to make more dua, so I did. Then she was responding well to chemo. I thought, "Oh God, my prayers have been answered." But the surgery didn't go well. I was devastated. They said it's unresectable and to continue chemo. I managed to get my hopes up again and kept making dua and praying. She continued chemo and then stopped because she had enough cycles and started maintenance therapy. During that time, things felt a bit stable and I kept praying, "Please, please God, don't bring me back to the starting point of this. Please don't scare me again with my mom." And then her blood test shows her cancer is progressing and not responding to maintenance, almost a year after all this started. Why isn't Allah answering my duas? I'm not a bad person, I swear, and this year I've really tried to be good and changed for the better in my deen. I pray and give sadaqah regularly, etc. Am I doing something that's causing this punishment? I can't think of any major sin I've done. I really don't think I have. I'm so tired and so scared and feel so guilty that I might be causing all this pain to my mom. What can I do to get my duas answered? Because almost a year of tahajjud and duas hasn't been working. I'm so sad and scared of losing my mom. I love her so much despite her temper and everything else, and I feel so guilty about all our fights before her diagnosis. Do you think this is my sin? Fighting with her before? Even now sometimes she gets mad at me, but I apologize immediately, not like before... Do you think this is why? I don't see an outcome of my life. Do you think this is my sin? But Allah doesn't sin us on sad thoughts, right? Every time I get my hopes up that my duas have been answered, something happens. So sorry for this vent, and I probably don't make sense throughout due to me crying while typing this.