A lot of this is going to depend on how long ago your drug use was and how often you used. Did you try it once or were you doing using pot on a weekly basis? How can you prove you won’t ever do it again?
With regards to your foreign background I think you’ll be fine provided you can prove that your loyalties are with the US. Even a basic understanding of history would indicate that someone of your background would. Have you visited Iraq or the Near East since then?
I’m a naturalized citizen and I had some mild drug use in college so I get where you’re coming from. For better or for worse we have a higher burden of proof than others but if your intentions are pure and you are honest, things will work out.
Hope this helps.