Hello. Thanks for mapping. 
A few remarks. 
1. Map more precise. do not oversize.
2, Check this picture.
https://drive.google.com/file/d/1Yi24_3r_C9dljCiIPjJEkTYTX3yWrxg4/view?usp=sharing

You mapped several objects as a building.  see the red arrows. 
These are no buildings.
Best regards

