Didn't seem like excessive enemies to me. not sure how many you were aiming for so dont know if i got "Way more" or what you intended.
Liked the map well laid out etc. my comments would be 20 objects hidden in a map that size I could look all day and not find them all LOL. I stopped looking after about 8 or 10. If i were you I'd bunch them closer and use the rest of that map to keep telling more story. (or maybe there is more story but i got tired of looking for the keys)
Also try to theme some of the terrain - especially in the caves so its not all the default green grass/grey rock. you could even theme areas which would help the player remember if they looked there or had been there or not. Or use a sky changer to make it darker when player enters caves etc.
I did like the layout as I said however.