Wanting to skip bleeding during your hike makes sense. But switching from one hormone medicine to another needs to line up with your ongoing treatment for secondary amenorrhea, so it isn't something to plan alone.
Next Steps
Ask your prescribing doctor before your last MPA dose on the 19th about switching to norethisterone and the right timing for you.
Health Tips
Timing this wrong can cause breakthrough bleeding or unsettle your cycle further, so avoid starting it on your own.