My first published YA novel was required summer reading at a high school in 2010.
However...
1. It was the high school in the town where I live, which my daughter was attending. That is, I had a personal connection there.
2. I had done a visit there earlier in the year and had spoken extensively with the librarian, who persuaded the English department to "support a local author"
3. It was the year the Phoebe Prince case occurred, and bullying was hugely on everyone's mind. The Massachusetts laws regarding bullying in public schools were passed. And my book had a strong anti-bullying component. (The school also invited me in that fall to present an anti-bullying assembly.)
4. As a former teacher, I had some clue as to curriculum guidelines, and I was able to develop a teacher's guide to accompany the book that touched on some of the high school English curriculum requirements.
Also, my book was not self-published (it came from a small, royalty-paying publisher), and the school went so far as to contact the publisher for more information about the book before they assigned it.
It is not easy to have a book placed on a summer reading list. School districts have set requirements, which have to meet state requirements, which have to align with federal guidelines. Contacting schools willy-nilly asking them to use your book in their curriculum will not be likely to gain you any positive attention.