SOLVED. YA book about a girl with dyslexia. Read in early 90s. Cover: yellow? [s]

[Zev]

Her name might have been Andrea and she may have been blond. I think her teachers knew about her dyslexia, but I don't think they cared. She wasn't getting support around it, and was embarrassed. She was a skilled illustrator and was drawing a picture during class of a construction site near the school. She drew a sign that said "detour", only the "d" was backward. A boy who was constantly mean to her sat behind her and leaned over the drawing. "What's a betour?" he asked, smirking. The teacher heard this and took the drawing away. The girl thought to herself, "The d went this way, and the b went that way, and I forgot. I feel like throwing up."

Later, she goes to or hosts a sleepover and she and her friends have tons of fun. They watch good movies and do silly things. One girl winds up with her foot in the popcorn bowl, and another takes a picture. They all pass it around the next day, laughing about how much fun they had. The boy who is regularly mean to the dyslexic girl sees the picture and asks if he can come to the next sleepover. She brushes him off.

She dresses up for Halloween as a football player and takes the kid she babysits for, with her. One man gives them packs of sunflower seeds. The kid instantly has a screaming and kicking tantrum. "Tanny, tanny, tanny!" "What?" the man asks the girl. She scoops up the kid and explains, "He wants candy." The man shakes his head. "Here's an extra pack for you, kid." She likes sunflower seeds, so this is a treat for her.

This took place in the USA, maybe the Midwest? I'll comment if I remember anything else.

[Daisy]

Some of this doesn't match, but the dyslexic girl and the "betour" sign are from Sixth Grade Can Really Kill You. The girl's name is Helen.

....but the "betour" sign wasn't part of a drawing of a construction site; it was on a web of string (?) that Helen wove between two desks.

[Zev]

Yes! Thank you!