It seems that my situation

is much better. A couple of months ago, my supervisor came to me asking me whether I want to extend my contract. I told her I need some time to think about it. Since I am not very interested in my work here, I told her that I would like to find a new position later. She wrote a supportive letter for me and finally I got an offer from another university. They are currently doing the paperwork for me for H1 transfer. Furthermore, my supervisor extended my current contract for one more month to make sure that I will have enough time to process my visa transfer. BTW, my supervisor is very satisfied with my work in her lab. Anyway, I am very lucky to meet a nice supervisor. Thanks my boss!