Some mistakes I have made

During the Project I’m currently managing I’m learning about some practices that I should improve. Basically these are:

• I had to define the third level of the WBS, only two levels were not enough, with three levels some assignments should be clearer and the monitoring of the project should be easy for me.
• The estimation on some of the activities were not right and it is because I didn’t take into account the quality level that these functionalities should reach (To reach it, takes time).
• I started the quality plan in the middle of the Project, not in the planning phase. It has provoked a delay in the deliver milestone.
• The risk management plan was exhaustively studied but I didn’t schedule the mitigation activities on the Gannt chart.

So much things to improve?? yes