Request #72

Looking for a book I read as a teen in the late 90s most likely. Probably published between 80s-99. The cover was a picture of a teenage girl.. dressed kinda funky in converses(?) and a plaid skirt(I think!). So it’s a lighthearted YA romance… the main character is MacKenzie(?) think.. and her best friend is Devon. She is in love with her neighbor… he only sees her as a close friend bc he’s a little older. So she sets out to make him fall in love with her by trying to be like any girl he’s currently seeing.. she gets into a lot of awkward moments. I remember random pieces like she buys a sweater dress and uses socks for bust enhancement.. which fall out when she is with him. Her friend always complains about her thighs. They were both only children and their families are really close. Please help.. searched for ages and no luck. Thanks!