There is nothing wrong with the person who prays Witr in the first part of the night or the middle of the night offering any Nafl (supererogatory) prayers he wants after Witr even though it is recommended for the last of his prayer at night to be Witr.

The one who prays eleven rak’ahs is doing well and is following the Sunnah. Whoever makes the recitation shorter and increases the number of rak’ahs is also doing well. For more, please see the detailed answer.