If you are gonna get TA/RA, your best option will be to collect your I20 and apply for visa from Nepal or Canada. That way your you can be employed as a TA/RA by your school. However, if you dont wanna take the risk of traveling out of US, then you can apply fot change of status to f1. That may take several months but you can still take your classes. Only after being approved, you are eligible to apply for TA/RA. Regarding visitor visa application to Canada, it is an easy online process. You dont have to attend an in person interview, and it takes 1.5-2 months. Good luck.