Hi ellameno,
Welcome to the Mattress Forum! 
I’m sorry you’re having issues sleeping comfortably on your current memory foam mattress.
Usually, someone who sleeps in the prone (stomach) position needs a surface that is firmer and less forgiving. There’s a bit more information about common sleeping positions and appropriate sleeps surfaces here.
The information you’re providing seems to indicate you’re desiring more plushness on the top of your current mattress. While certainly not the norm for someone sleeping upon their stomach, if you do desire a more substantial plush topper, you may wish to investigate latex instead of convoluted 3 lb memory foam (like your topper from Kohls), or a solid (non-convoluted) memory foam topper of at least a 4 lb density. There is more information about choosing a topper in post #2 here and the topper guidelines it links to that can help guide you through selecting a new topper for your mattress.
Phoenix