QR will get you to AMS one way or another, and that should be before your afternoon flight, so stick with what you have right now. Really AMS is a complete mess at present.

Although you can't cancel Avios bookings within 24 hours, you can generally reassign them if there is Avios availability, which you'll need to do on the phone probably. There will be a change fee involved, but it's often useful.

I'd be inclined to wait for clarity on the QR flight first; basically you call them or use online chat and you don't accept the itinerary change. If you're in Doha you may be able to do this at a transfer desk. I would expect resistance and difficulty personally, but doesn't mean you don't try.