Am I required to offer a sacrifice (hady/udhiyah) after performing several 'Umrahs and residing in Makkah, and what should I do if I am unable to do so?

The Udhiyah (sacrifice) is recommended, not obligatory, according to the majority of scholars, and it is prescribed for the people of Mecca and others. So, whoever is able to offer it, let him sacrifice, and he will be rewarded. And whoever is not able, there is no blame upon him for not offering it. If a Muslim performs Hajj and wishes to offer a sacrifice in Mecca, or appoint someone to slaughter the Udhiyah on his behalf in his own country, there is no harm in that, and he will be rewarded.