Doubts (waswas) are a common trial; the Prophet ﷺ advised seeking refuge in Allah and turning away from the whisper rather than dwelling on it. Learning from reliable scholars, reflecting on the signs of creation, and keeping firm worship all strengthen certainty.
Evidence — the daleel
Sahih al-Bukhari 3276 Ṣaḥīḥ
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.