All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Doubting about the number of rounds of Sa’y or doubting about the place where one had started it, if this happens after finishing it, then this does not have any effect. An-Nawawi said about someone who doubts the number of the rounds of Sa’y or Tawaaf (circumambulation around the Ka’bah): “…If he doubts after having finished it, then he is not required to do anything….”
Moreover, Shaykh Ibn ‘Uthaymeen said: “A rule: Interrupting the intention of an act of worship after having performed it does not have any effect. Similarly, doubting after finishing an act of worship whether one doubted about having made the intention or not or about performing some parts of the act of worship or not, then this does not have any effect unless one is absolutely certain.”
Also, there is no harm for interrupting the Sa’y in order to pray, and then continuing the Sa’y afterwards, and it [Sa’y] does not become invalidated for doing so. An-Nawawi said: “If an obligatory prayer is established while a person is performing Sa’y, he should interrupt his Sa’y and pray and then he should continue from where he stopped. This is our view in our School [Ash-Shaafi’i] and this is the view of the majority of the scholars among whom are Ibn ‘Umar, his son Saalim, ‘Attaa’, Abu Haneefah, and Abu Thawr. Also, Ibn Al-Munthir said: “This is the view of the majority of the scholars.”
Therefore, we hope that your Sa’y is valid, Allaah willing, and what you mentioned does not necessitate any expiation. For more benefit, please refer to Fatwa 130430.
Allaah Knows best.