If you've been maintaining your F1 status and are working where you're supposed to (i.e. in STEM field), you'll be fine. There's always some risk but I don't think you'll have any issues. My experience is slightly different - I went to Nepal while I was on OPT, but my F1 was still unexpired. Came back, worked for another 1.5 years (my F1 also expired during this year), started gradschool, went back home about a year later and entered US with a new/renewed F1.

You should be fine, just don't forget to get the signature on your current I-20 before you go to Nepal, make sure you have that letter from your employer, and carry all of your I-20s, EAD cards with you