Is it permissible for me to complete the seven remaining days of my Ramadan make-up fast after mid-Sha’ban, especially since I have already fasted three of those days after this date, and do I have to make up the three days that I fasted if it is not permissible to fast after mid-Sha’ban except for those accustomed to fasting?

Fasting is forbidden in the second half of Sha'ban, based on the Prophet's (peace and blessings be upon him) saying: "When Sha'ban is halfway through, do not fast." Three cases are exempted from this: one who has a regular habit of fasting, such as fasting on Mondays and Thursdays; one who started fasting before mid-Sha'ban and continued it past the halfway point; and one who is fasting to make up for Ramadan, or fulfilling a vow, or an expiation.

Accordingly, making up for Ramadan in the second half of Sha'ban is permissible and valid.