Have patience. It will take a while for your GD to reveal Themselves.
Seriously, my partner - who has been a SS for around five years - has only discovered his GD recently. After he helped me discover my GD. And I've been dedicated for... almost two years.
So it really does depend. I know everyone says this. But really pay attention to the Gods you feel drawn to. I didn't think that... this particular God could be my GD. Guess what. He is! Be open minded with this whole thing.
You can try finding out. There are pendulums. And... there's tarot. That's how I found out.
The most important thing is to be patient. You won't find out if They don't want you to find out.