Have I been under immigration proceedings in the U.S?

No, you've never been in proceedings. that's a formal process that takes place in the US. if you had been in proceedings you wouldn't need to ask. Of course, doing things the way you did, it makes you look guilty, like you really weren't your father's child. most of the time when someone refuses to take a DNA test, it's because they know they'll fail. good thing for you, you were under 18 at the time, so they won't hold you responsible. good thing you aren't being petitioned by your father again, as well.