Worse comes to worse, you ask and you'll simply have to wait until the flight attendant is done with their safety briefing -- the belt extenders are what they use to demo how to unbuckle your seat belt. (And who do they need to demo this for anyway? The Amish? Who doesn't know instinctively how to unbuckle a seat belt?). I'm pooh sized as well, but I manage to fit. Only on one flight did I have a problem -- and it was a CLE to ORD flight when the lady sitting in the window seat truly should have been made to purchase two tickets. My seat belt latch was under her posterior! I spent the entire flight unbelted, and tilted sideways in my seat so I'd fit! I know, I should have complained and been moved for safety but it was a full flight and I had to be in Chicago that afternoon for a business meeting. I'll never forget that flight, and I've never let corporate pick my seat since!