Same here, for now I'm trying to sing the major second from the bass note to tell if it's a sus 2, but still get it wrong. When I help myself with the piano it gets more obvious so I guess ultimately this will become simpler.

Been doing exactly the same thing, either with the maj second or the perfect fourth. Still getting it wrong a bunch of times.

Ditto - I find the sus2 higher note rings out for me and that helps a bit. Used to be so easy when there was only a sus4...

Somehow now i can always guess sus2 chords, they sound like a very specific windows 10 sound effect.

In my case, I listen to the highest and lowest notes.
And find M2.
I think you'll find a way soon.