That's definitely weird!
Log into your email provider's website via your web browser. (i.e. DON'T use any type of email app). See if your missing emails are in the 'Sent' folder there.
If they are then there's some sort of problem with the syncing between your iPad's email app and your mail provider's server. (All I can suggest for that, I'm afraid, is yet another 'delete & recreate' attempt).
If your emails aren't in the 'Sent' folder when you use web access then there's a problem with your provider's system, which you'll need to contact them about.