Use this one-
'category__not_in' => array( 93, 94, 95 ),
instead of-
'category_not_in' => 93,
Note: The term is category__not_in, not category_not_in. Use 2 underscores after category.
Edit: You are using-
'offset' => 1
That forces to show posts from 2nd one (skips the first post). So, it’s showing one post less! If you use 'offset' => 3, then it will start from 4th post.
Hope you understand.