I'll tell you the steps I did instead of working with what you have since I'm not sure how your layers are set up. Just let me know if any of this is confusing!
1. Make your two layers, transparent layer on the bottom, with the white layer on top.
2. Create a shape layer, using a heart.
3. Control+click on the vector mask thumbnail with the heart. This will select the heart shape.
4. Press Shift+F6 to go to the feather menu. Type the number of pixels you want the feather effect to be. If you type too big of a number, the heart shape will not have a big point in the middle. You can always press Control+Z and enter a smaller number if need be.
5. Once you see the desired heart shape selection with your feathering in place, hide the top shape layer by clicking on the eye icon to the left of the layer.
6. Select the white layer, then just press delete. This will delete the heart shape from the white layer, allowing transparency to show through.
Hope that helped! Let me know if you have any trouble with my directions
