All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
The Tawaf al-Ifadah is one of the pillars of Hajj, and one`s Hajj isn`t considered complete without performing it. According to jurists, there is no specific time limit for its completion, and it remains obligatory for the rest of one's life. Imam al-Nawawi, may Allah have mercy on him, mentioned in the context of listing the pillars of Hajj that "the Tawaf and the Sa'i have no specific time limit." Imam al-Khateeb al-Shirbini, may Allah have mercy on him, commented on this by saying, "And it remains obligatory for the person as long as they are alive" [Mughni al-Muhtaj, Vol. 6/P.62].
If the situation is as described in the question, then you are still in a state of Ihram, and you have only performed the initial form of Tahlul (Removing the restrictions of Ihram), which allows you to resume all the prohibited acts of Ihram except those related to sexual intercourse with your spouse. If you are physically and financially able to complete the remaining rites of Hajj, then it is obligatory for you to return to Mecca. However, you are not required to enter the state of Ihram again when passing Miqat (the designated boundary for entering the state of Ihram), as you are already in the state of Ihram. You should perform the Tawaf Al-Ifadah (the circumambulation of the Kaaba) and then perform the Sa'i between Safa and Marwah, assuming that you are performing Hajj al-Tamattu'. This will complete your Hajj, and you will then be in a state of Tahlul.
If you are unable to complete the remaining rites of Hajj due to illness or other valid reasons and have become like a "Ma'zoub" (one who is unable to perform Hajj on their own), it is permissible for you to appoint someone else to perform the remaining rites on your behalf. This includes the Tawaf al-Ifadah (circumambulation of the Kaaba) and Sa'i (the ritual of walking between Safa and Marwah. Sheikh al-Islam al-Shihab al-Ramli, a prominent Shafi'i scholar, stated that it is permissible and even obligatory for the person who is unable to complete specific rites of Hajj to delegate someone else to do so on their behalf. {Fatawa Ar-Ramli, Vol.2, Page 93}.
Regarding the Tawaf Al-Wadaa (Farewell Tawaf), there is a difference of opinion among scholars regarding whether it is obligatory (wajib) or recommended (mustahabb). To make it easier for the above questioner, it can be considered as recommended (mustahabb). This means that you are not obligated to perform it, and you don't have to offer a sacrifice for not performing it. You aren`t considered in a state of Ihsar (This refers to the hindrances that the pilgrim may come across when he/she is on the way to perform Hajj or Umrah) because illness isn`t a reason for that and because you have already stood at Arafat and continued with your Hajj. And Allah the Almighty knows best.