Originally Posted by NattUhhLee

Seeing as the petition was approved, you should be able to use the 245i grandfathering. But just be aware that as a Sibling of a US Citizen, you would be categorized as a F4 visa preference which as of October Visa bulletin is backlogged to 2007.

Two questions: Are you currently married? And has your sister tried petitioning for your mother yet? Assuming she also entered with a visa, your mother (as a parent of a US Citizen) would be immediately eligible for AOS. And then upon receiving her Green Card could petition you as an unmarried adult child of a Permanent Resident which has a shorter backlog, current Visa Bulletin shows 2016. So a 5-6 year wait in comparison to a 14-15 year wait..