Dropping out of school and leaving is not an issue at all. You didn't overstay or nothing. You will be able to apply for any visa don't worry. Hey, life happens. Not everybody is fortunate enough to go through this process without issues. You're fine. You put your education on hold to tend to your family when they needed you. On the bright side, it will be easier for you to get a US visa since you have been here legally, left in a legal way, and didn't misuse your visa.