Some of your posts are answers, which don't have the title field populated.
You can left join back to
ParentId and then coalesce the title field if you want the title displayed in all cases, or select
Posts.Id AS [Post Link], which will give you the title as a link to the post in question.
Also note that usernames are not unique, so generally you'd want to select using your user ID as input, which Data Explorer will attempt to guess for you automatically based on your email hash if you're a registered user and you do something like
WHERE Posts.OwnerUserId == ##UserId##.