my above comments were entirely for AOS.

If you are planning to do CP, as explained by deoneofkind, It will be faster but you have to return to Nepal. The risk is, if you got rejected in KTM (god Forbid!) you would never be able to come back to USA  as applying for DV is an intent to stay in US and its a contradiction to F1 visa..

Also, there is a form that asks you if you had worked illegally in US (I think its I485) while applying for change of status. Now, its entirely upto you to disclose if you ever worked in OC. If you do not, either way can lead you into circumstances, as they might check internally if you do not disclose (which is against the law too).

Good thing is, you have plenty of time. Prolly until  June next year. Again, i advice you to consult a lawyer whatsoever.

P.s. I am not trying to scare crap out of you. I am a pessimist. Its just to make you realize, its not an easy fruit to pick. There are risks involved and your situation have made it even more complicated. Ever heard of people getting first letter but the not the second letter and getting stuck  back in Nepal?