I think you found Kristy's voice quite nicely - she was the first one I thought of when I started reading the story, even before you dropped hints as to the speaker's identity :)

Always happy to peddle Thomas brothers fic, and Sam/Stacey shipping! I LOLed at this line, especially: You think she'll say yes?' He actually asked that! Of course she'll say yes. Even if she hadn't been doodling 'Mrs. Sam Thomas' on notebooks and things since we were twelve, the ring alone would do it. Hehehehe...so perfectly Kristy!