Although I;m mostly into yaoi, I do adore webtoons like these!
I can relate easily because even I and others have problems with our beauty and how we appear ourselves. It's very slow with the romance and the main character's personality is perfect! Stubborn and clueless.
If you want a webtoon that tells a story of a girl who finds herself unattractive and then makes herself seem attractive, this one is your best bet.
My ID is Gangnam Beauty