You might want to start off making maps at 128x128 which is standard and most used. Also, use Lost Temple's 8-8-6 or 8-7-7 style of placing minerals and expansions. 8 minerals and gas at main and 7 minerals and gas for natural expansion. Third would be a min only expo. Also, for the gas nodes, place them so that the Command Center/Hatch/Nexus can be right next to it as well as the minerals. Players don't like lone gas nodes that much.
The way the map is right now, there won't be any room for large armies to battle since there are so many chokes connecting small islands on such a small map. Try using my suggestions and learning how to make a balanced map.