Hello! I want to know if I’m using the particles and the different words for “and” well. And if not, what are my mistakes and how can I fix them? Thank you very much!

어머니는 슈퍼마켓에 우유하고 알을 샀어요.

Mom bought milk and eggs at the supermarket.

저는 시, 소설, 그리고 단편소설을 써요.

I write poems, novels, and short stories.

저는 많이 책을 읽어요. 그래서 읽는 사람 이에요.

I read a lot of books. Therefore, I am a reader.