Having doubts about Islam and struggling with my faith

Assalamu alaikum. I've been facing a lot of inner turmoil lately. It's been maybe a month, perhaps longer. I feel like my life is full of sins-I watch inappropriate things and get pulled into wrongdoing. It's gotten so bad that I'm starting to question if Islam is actually the truth, and even whether Allah exists. I often defend Islam, refuting false claims and attacks on our beloved Prophet (peace be upon him), but inside I'm wrestling with doubt. I need clarity and certainty. How can I be truly convinced that atheists are wrong? I’m scared-what if when I die there’s just nothing, and they were right? I haven't prayed consistently or felt a connection to Allah. How do we believe in something unseen? I know that’s what faith is, but how can we be sure we're on the right path?...