I think what you've got here does a good job of feeling like something an adventurer or miner sketched out: the style, the weathered parchment, and the table might be the most obvious indicators of that. I think from that perspective, it's OK that you don't have many floor details, and if you did it might actually detract from the style of the map. If there's one thing that could use more distinction, it's maybe that chasm in the top center: I feel like if a person was actually sketching this by hand, they might color it in or something to indicate the depth. Maybe try just shading that part darker and see how that looks to you?

If this was used for tabletop gaming, I could see this as a great player handout, maybe from a grizzled prospector who got chased out of the mine by something frightening.