Answer:

عَنْ مُحَمَّدِ بْنِ أَحْمَدَ رَفَعَهُ قَالَ قَالَ أَبُو عَبْدِ اللَّهِ علیه السلام :

إِذَا شَکَکْتَ فِی تَسْبِیحِ فَاطِمَةَ صلوات الله علیها فَأَعِدْ

📚 Al-Kafi, Vol. 6, Page 225

Imam Sadiq (peace be upon him) said: If you doubt during the Tasbih of Lady Fatimah (peace be upon her), then repeat it.

✅ Based on the above narration, if we doubt the count of the Tasbih of Lady Fatimah (peace be upon her), we should start it from the beginning.

اللَّهُمَّ فَصَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْرَ