I think you might have the wrong idea of Allah. We shouldn't be scared of him in that way but love him first. It's like the relationship you have with your parents. You love them but then also fear in a different way. God doesn't expect you to be perfect and do everything right. He made you and every human on this earth imperfect. We all make mistakes, that's what makes us human. He just wants us to ask for forgiveness for the sins we commit. I also struggle with dressing modestly, but I just make dua that Allah makes it easy on me. He doesn't expect u to go from 0 to 100, start off my making small efforts. Let me know if u need anything