You probably got a bit of damage, but unlikely anything significant. People shoot guns without hearing protection all the time without much problem, it's only after repeatedly exposing your ears to it will you permanently develop NIHL and tinnitus

There is a very good chance it will completely go away over the next few days. Make sure to bring a pair of really good earmuffs next time, possibly in addition to some foam plugs.

There's no need for steroids BTW. It can be helpful in some cases but the evidence that it helps is limited and there's actually a small chance it might make things worse. If your ears are healing quickly on there own then just leave them alone.