Wallflower Main Character, Struggles of Being Shy, Introvert

[Emily]

Contemporary YA is my life. Most of mine are kinda sad though. For now I'm thinking of Hold Still These Gentle Wounds Fall for Anything 100 Sideways Miles Simon vs. the Homo Sapiens Agenda

[Eliene]

Lirael by Garth Nix is a YA fantasy that is the second book in the Abhorsen series. It's main character is an introvert that is shy. Her personality is a key point in the novel. I hope it's what you're looking for

[Lisa]

Well, she's not really contemporary or YA, but you might like Barbara Pym's novels, especially Excellent Women.

[Jenna]

Oh, yes, loved that book -- and A.N. Wilson's introduction to one of the editions was perfectly lovely in itself. Second Lisa's suggestion.

[Lobstergirl, au gratin]

Washington Square has a pretty wallflowery protagonist. It's a classic and Henry James, but actually it's not that long (under 200 pages) or dense. I'm only halfway through so maybe at the end she busts out of her shell and becomes a stripper...we'll see.

[Lobstergirl, au gratin]

Alberta and Jacob is a Norwegian classic, probably the most introverted protagonist I have come across. It's coming of age but not YA. The protagonist is maybe 16-19 and it covers maybe a year of her life. There is a tiny bit of romance, a very tiny bit.

[Rainbowheart]

Someday This Pain Will Be Useful to You

[Rachie2929]

Fangirl, perhaps?
Unbreak My Heart
Gorgeous
I'm not entirely sure about those anymore, since it's been a while since I read them, and my long-term memory and details don't generally play nice.
Also, maybe take a look at this topic, I'm not sure if it's exactly what you want https://www.goodreads.com/topic/show/...

[Luxshi]

Introductions by C.L.Stone is a good book. The main character, heroine is shy. This is the first book of an ongoing series. It is an excellent book. The series evolves to a polygamy relationship, but it is a young adult book series.
@https://www.goodreads.com/book/show/1...

[The Reading Raccoon]

Have you read Turtles All The Way Down by John Green? Main character has anxiety and issues which affects her social life.

[Lobstergirl, au gratin]

A Misalliance

[Lobstergirl, au gratin]

Where the Crawdads Sing