@Sapkota123 bro!, i'm on the same boat, the difference is F1 vs H1, and i did consult some attorneys. You will need an advanced parole document to travel to Nepal. It takes at least 90 days for advanced parole documents to be approved.
The reason has to be some sort of emergency situation. If the situation is serious and you don't have time to wait you can expedite your proceedings and go to USCIS in person and apply, but there's no guarantee. They might ask for more evidence if your supporting docs are not compelling enough.

Given your TPS is pending like mine, it might take more than 90days for it to be approved. You are still under F1 at the moment since ur TPS is still pending, even if u have an ead. So If you travel without AP, as long as you have a valid F1 you should not have a problem. If questions asked at POE, you must state the reason you had to travel. Your TPS case will be regarded abandoned once you leave the country and lose any TPS benefits.

If you receive or already have AP, you can use that to travel and enter the US as a parolee status.

just sharing few things i learnt recently.

Goodluck.