I performed Hajj and Umrah in 1994, I'm not sure if I did Tawaf al-Ifada or not. This year I went to Mecca again for Hajj, and did Tawaf al-Ifada for the last time. Is that good enough or I have to sacrifice a lamb? Please let me know.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

As a rule, the rulings of the Sharee'ah are based on facts and certainty. In other words, accidental doubts have no influence on one's worship since one is originally supposed to perform worship in full. For example, if one performs Hajj and returns to his country, and then he has doubts about whether or not he has performed Tawaaf (circumambulation around the Ka'bah), then he should not take such doubt into consideration. Another example is if one has performed the Thuhr prayer and finished it and then he has doubts about how many Rak'ahs he has done (three or four), he should not take such doubts into account since he is originally supposed to perform complete prayer.

Based on the above statement, you are not required to perform Tawaaf Al-Ifaadhah or offer a sacrifice.

Allah knows best.