As you said, you have already sold your flesh and soul to the devil. :) Now, you want to reclaim a piece back.
Still, there is something you can do. You need to 具体问题具体分析. Do not be like ntking --- since he is good at hammer, everything in the world is nail to him. :))) No offense, ntking is one of my favorite stars in this forum. When he speaks, 我只剩下耳朵, in 含娜's words.
(1) Sounds like a small company. How big is it? Is it in an immigrat-friendly area such as CA?
(2) How was its reputation in sponsoring GC historically? Check out with someone.
(3) How much do you know your direct boss's altitute and the HR personnel's altitue towards immigration?
Based on the information, you can come up with the revisionary version with help from people here.
Wish you get GC soon.