Something’s not right with me-just venting

Honestly, I feel like my mind is in shambles and I don’t know how to fix it. I stayed away from this sin for two years, but I slipped back into it just before Ramadan because of something I picked up last year. After Ramadan, I couldn’t stop, and I keep telling myself I’ll quit, but I haven’t, and it’s wrecking my life. I make du’a for stuff-which is already hard for me since I feel guilty and struggle to even make du’a-and it feels like nothing comes true. Like, I’ll even pray tahajjud, which everyone says is like a "cheat code," but the things I ask for just don’t happen. Life’s been one failure after another: didn’t get into my top two university programs, missed out on a scholarship I worked so hard for, bombed tests at school. Maybe I messed up some details-like not studying enough or not being thorough in my application-but still… I shouldn’t be failing this badly. This is really the lowest point I’ve ever hit, and I know it’s because of how careless I’ve been. I get it, I’m facing the consequences, but how on earth do I break out of this cycle? I’m starting university in the fall, and if things keep going like this, it’s truly over. I realize I’ve lost my way, but deep down I believe I have the ability to do better. It’s been messing with my mind, though-honestly, I think I fell back into the sin because things weren’t going well at school in the first semester. That’s another story, but doing this definitely isn’t making anything better. I also make du’a asking Allah to remove this darkness I feel inside me (why else would I be acting like this?), but I just can’t pull myself out of this rut. I’m truly going crazy. *Sigh* May Allah guide whoever reads this to give me some sincere advice.