Your OPT gets automatically cancelled once you transfer your sevis to another institution. If you have a vaild visa, then you should not have problem travelling to Nepal with a new i20 and travel signature. And one more point, the burden is on you to maintain your status and not your DSO. You have to know the rules of OPT. They may be willing to help you but are not required to. If nothing works out just transfer to your new university and then go to Nepal on summer break, Or Take a semester off.
Here's an info from a  university:
http://www.oiss.wayne.edu/immigration-visas/f-1-optional.php

 Maxpayne,

i sorted out all the issues. My DSO helped me out. Thanks for the suggestion.

 desh, sounds like you the stupid one

I don't think you can travel outside the country on OPT without having a job. Even if you have a job, you must have a valid visa. This was my friend's case. But if you have a valid visa and new I-20, you should be alright for back & forth. Good Luck !

i will have a new I-20 before i leave the country and i do have valid visa.