Day 1: Sarria to Puente la Reina
This stage runs from West to East: about 564 km. It's gonna be a long day.
Day 2: Puente la Reina to Belorado
Right direction: from East to West, 137 km. Still a long day.
Day 3: Belorado to Arcas de Valdespina
This runs from East to West. Sounds good, only Valdespina is not on the
Camino Frances. But pretty close: it's about 16 km. south of Frómista. Belorado to Frómista: 110 km. Then 16 km. to Valdespina.
Day 4: Arcas de Valdespina to Nájera
In the morning first 16 km. back to Frómista to continue on the Frances. Then from Frómista to Nájera: back to where you came from, since this runs from West to East, a stage of about 155 km.
Day 5: Nájera to Logroño
And again a bit further away from Santiago, since this runs from West to East. But at least it's a doable distance for one day: 16,6 km.
Day 6: Logroño to Santiago de Compostela
What a finish: in the right direction again (East to West), for a glorious stage of 600 km.
If you'd like a second opinion, try the planning tool of Godesalco:
Perfiles altitudinales, planificación de etapas y archivos GPS para el
Camino de Santiago.
Happy planning!