Sharing Some Heavy Thoughts This Ramadan

Assalamu alaikum warahmatullahi wabarakatuh. I was raised Muslim but only truly began my journey of faith around 16. I live in a place where most people are Muslim, but only a few live by it seriously. I need to get some things off my chest. I was exposed to inappropriate things, like certain videos and talk, from neighbors when I was very young-around 6. It affected me deeply. I was always a studious kid, and by the fifth grade, I got into a great boarding school. There, I learned so much-English, computers, the internet-it opened up the world for me, but it also gave me more access to those haram videos. I fell into the habit of self-gratification. It wasn't constant, but it was there. When I was 15, I had a serious health issue with my bladder. The tests and treatment were really hard and costly, and I eventually had surgery, alhamdulillah, I recovered. Throughout that time, I believed it might be a test or a reminder from Allah SWT about my actions. I made a sincere promise to turn back to Him. I learned my salah and, by His grace, started praying five times a day-and I still do, alhamdulillah. But the struggle with that habit never fully went away. It comes back, sometimes during Ramadan too, and I feel so weak, relapsing about once a week. I can't seem to go longer than 7 or 8 days. Now, to the doubts that trouble my heart. My mind sometimes floods with 'what ifs'-what if I'm wrong? What if there's nothing after this life? What is my proof of Allah's existence? These thoughts even come during salah, and I seek Allah's forgiveness for them. There are also some Islamic concepts I think about a lot, like the arithmetic of reward: If reading Surah Al-Ikhlas three times equals the reward of the whole Quran, then why don't we all just do that often? Or, if dealing with riba is so severe, how do we navigate a world so full of it? Does a single sin erase all good deeds? Does an action without pure intention count for nothing? These questions sometimes shake my iman. I have deep respect for Islam. But my nafs is strong. Lowering my gaze is a constant battle, especially where I study now. The whispers (waswas) are real. And that old habit... I've tried to stop so many times. This struggle has led me to feel very low, even having dark thoughts at times. I feel worthless. When I pray after falling into sin, I feel like a hypocrite. I fear my intention to stop isn't purely for Allah's pleasure, but out of fear of poverty or other worldly consequences. That makes me feel like a munafiq. People say relapsing once a week is progress, but after two years, it feels like a trap. I feel my brain has been wired this way, and rewiring it is so hard. I also enjoy listening to music, which I know is discouraged. I sometimes slip in my speech. And I feel a deep loneliness and natural desires that are hard to manage Islamically. I've never been in a real relationship; a couple of brief, distant communications were all, nothing physical, alhamdulillah. I'm still chaste. Sometimes I wonder if the only reason I've avoided greater sins is because I lack the means, and maybe that's Allah's mercy protecting me. What I truly want is financial stability to help my family. We grew up with little, and seeing my mother struggle hurts my heart. I have this irrational thought: you must be a perfect Muslim or not one at all. But I know that's not right. I know I have a good heart. I cry over my mistakes. I make sincere dua. I love animals. I love the peace of the masjid and have attended every Taraweeh this Ramadan, alhamdulillah. But sometimes I wonder, what's the point if my mind wanders during prayer or I don't understand the Arabic? I feel regret for most of my sins-not all, and that scares me. I'm scared this regret might fade. These are my raw thoughts. Jazakum Allahu khairan for listening. Any kind advice is welcome.