hi gladgrams,
I agree with PrettyKitty, breaking thread is either tension and/or moving hands to quickly. Unfortunately, I don't know much about machines that adjust tension. can you override that. Or can you call store where you bought it and ask them for some hints.
If you don't want to free motion, I think I would accent the pinwheels part of it, outling that part, and let strips receed a bit.
I love quilt, you're grandson will love it. And I love his story about you living at the airport.
peel