He doubted whether he performed Tawaf-ul-Ifadah or not

Q: I performed Hajj 3 years ago, praise be to Allah. It was Ifrad Hajj (performing Hajj only) and I assumed Ihram (ritual state for Hajj or `Umrah) from the Miqat (site for entering the ritual state for Hajj or `Umrah) in Muharram Valley. I performed two Rak`ahs (units of Prayer) and said Talbiyah (devotional expressions chanted at certain times during Hajj and `Umrah) for Hajj. Then, I went to Makkah and made Tawaf-ul-Qudum (circumambulation of the Ka`bah on arrival in Makkah) and performed two Rak`ahs. I do not remember whether I performed the Sa`y (going between Safa and Marwah during Hajj and `Umrah) or not. On the eighth day I went to Mina and remained there until Fajr (Dawn) Prayer. Then, I moved with the pilgrims to `Arafah where I stayed until sunset. Then, I moved to Muzdalifah and stayed in it until Fajr Prayer. I went to throw Jamarat (stone pillars at which pebbles are thrown during Hajj) and threw Jamarat-ul-`Aqabah (the closest pebble-throwing area to Makkah) and shaved my head. I do not remember whether I performed Tawaf-ul-Ifadah (final obligatory circumambulation of the Ka`bah in Hajj) and Sa`y or not. I stayed the last three days in Mina to throw the Jamarat and after that I went to Makkah and performed Tawaf-ul-Wada` (circumambulation of the Ka`bah on leaving Makkah). Explain to me, may Allah reward you with the best, if I have to complete what I missed of Hajj to rid myself of the doubts? Is it obligatory on me to slaughter a sheep? Should I pay it to one poor person or to more? I want to repeat the Hajj, is this permissible? Which is better; to perform Ifrad Hajj (performing Hajj only), Qiran Hajj (combining Hajj and `Umrah without a break in between) or Tamattu` Hajj (`Umrah during the months of Hajj followed by Hajj in the same year with a break in between), in place of my first Hajj? Answer me, may Allah reward you with the best on me and Muslims!