الجواب وبالله التوفيق      

If a child is healthy and is not in a situation where there is an extreme need of the mother's milk, then breastfeeding shall be stopped at the 2 year mark. 

If however, there is a situation in which the mother's milk is absolutely needed for the child's health then breastfeeding can be continued until the child turns two and a half. After the age of two and a half, it is absolutely impermissible to continue breastfeeding the child.

(ولم یبح الإرضاع بعد مدتہ) لأنہ جزء آدمی والإنتفاع بہٖ لغیر ضرورۃ حرام علی الصحیح وفی الرد: انہ واجب إلی الإستغناء والمستحب إلی حولین وجائزإلی حولین ونصف (الدر مع الرد ۳۹۷/۴، کتاب النکاح باب الرضاع)

واللہاعلم  بالصواب