Yes, exactly right!
That feeling you had where you feel light but also heavy is very common for me too. It can feel like my back is made of led and my front is made of air.
You should try to get that feeling again and when you do, imagine your back pressing even heavier into your bed, so heavy that you're sinking within your mattress very slowly, deeper and deeper.... it will feel very strange like you're being split in half, one side heavy and the other very light.
if you do that for long enough, you will feel electric 'fuzzy' feelings in your legs and the rest of your body and after a while you will begin the split :)