SOLVED. Middle grade/children's novel about two best friends in a small town, one starts a consulting business and they have a falling out, girl with red braids on cover [s]

[Krista]

I read this book probably in the early 2000s, about a girl (I think with an uncommon name) who lived with her parents and (I think?) much younger siblings. She had red hair. Her best friend was much more traditionally attractive than her. They were maybe in 7th grade. The main character decides to start a consulting business (and meets with people at the public library?) and advertises in the paper so people won't know she's a child. At some point, she and her best friend have a fight, possibly about a boy. They live in a small town and everybody has the same first three numbers in their phone number, so they only have to tell each other the last four digits.

[Krista]

Bumping.

I think the main girl's name may have been Darcy and her friend's name starts with an L, but I'm not sure.

[Tab]

Totally Confidential fits.

I skimmed the book on Openlibrary. The "last 4 numbers" premise is mentioned.

[Krista]

That's totally it, thanks!