Wait, Rory and Amy were only 21 when they started traveling with the Doctor? I never put that together
I woulda put them at 25?
Amy was 7 years old when she first met the Doctor, as stated in her narration at the beginning of The Beast Below. Since she began travelling in the TARDIS 14 years later, that would make her 21.
Karen Gillan actually was 21 when The Eleventh Hour was filmed, and Arthur Darvill was 27.