coming of age series about 6th-8th grader, from2000s, navigating friends and boys

[Julia]

I read this series while in middle school like 10 years ago, series is definitely from the 2000s. the series had each book as she entered each new grade, I remember specifically that whatever region in the U.S. she was from had 6th grade in elementary school and her middle school was only 7th-8th grade. her boyfriend was a year older I believe, and they always used the word den to describe her family room (she had a birthday party and this stood out to me because I never heard that word used before) I also believe part of the main plot was she was losing her friend group as they navigated a new school, and struggled to balance friends and her new boyfriend.

[Rainbowheart]

The Winnie Years series?

Ten is the first book, but they continue until age 14.

[Rainbowheart]

The Elsie Edwards series?

Nothing's Fair in Fifth Grade is the first book.

It's much older than the 2000s, though.