Need Advice on Missing Dhuhr and Asr - JazakAllahu Khair

Assalamu Alaykum wa rahmatullahi wa barakatuh. I'm a Muslim, born into it Alhamdulillah, though my parents have left the faith. I wasn't practicing much before, but Alhamdulillah I met a sister who helped me learn more and I’ve been trying to become more religious and God-fearing. After researching Islam, I’m now trying to practice regularly. My main worry is living in a non-Muslim country where school finishes very late, so I often miss Dhuhr and Asr at their times and make them up when I get home. Even though I qada the prayers, I feel really guilty. I’ve tried finding a quiet corner at school to pray, even empty classrooms, but it’s hard to find a private place. I thought about asking my non-Muslim parents or teachers if I could use an empty room, but I’m scared they might react badly. They know I pray and are okay with it to some extent, but we’ve had small arguments about my faith before, so I’m not sure I have the courage to bring it up. I remind myself Allah Subhanahu wa Ta'ala knows my situation, but I still feel like I’m not doing enough. I heard from the Sunnah that Dhuhr and Asr can be combined or delayed in cases of work, travel, or need - is that correct, insha'Allah? Still, I feel sinful for missing the times. Am I considered sinful for this, since I make them up later? Does anyone have practical tips on how to handle praying during school hours, how to ask for a private space gently, or how to deal with the guilt? JazakAllahu Khair for any advice.