Like you get transported into an alternate universe where everything is almost same, but with tiny differences. The world looks normal to everyone and you’re the only one that have memories of the differences.
Do you think you would trust your memories or would you think you lost your mind?
I’d start looking for what filled their place: who graduated in their place? What person is filling their job position? Their brothers/sisters are the same? Wife/husband and kids? Etc.
If there is evidence of a filled void, I’d trust my memory; if not, I’d think I’ve gone crazy.