First of all, your wrote your introduction well. There's no critical grammar issue. But as you said, you repeated "저는". To make it more naturally, you can drop it once mentioned. In addition: 아녕하세요 -> 안녕하세요 (typo) 열심히 일하겠습니다 -> ? "열심히 일하겠습니다" means "I will work hard". I think it does not fit with the context. If you want to say "I will do my best", you may use "열심히 하겠습니다". Result 안녕하세요. 저는 미국에서 온 에밀리입니다. 한국어를 공부하고 있습니다. 감사합니다.