Hi and welcome here on this forum .I see that this is your first post.
I'm sure Norte pilgrims will chime in and give you up to date information.
I did not walk the Norte but from experience I know that busschedules in smaller towns are limited on a Sunday. So you are lucky that on that route you have a least one bus that day.
Did you book refundable rooms? I ask this because there might be a chance that you have to change your schedule en route while walking? And no I'm not talking about major incidents but you might experience some minor foot issues or a tummybug and the likes.
IMHO on Camino you have to take into consideration that even the best made plans need some rescheduling.
A good tool to plan your travels.
Discover how to get anywhere by searching plane, train, bus, car and ferry routes
For local taxis.
Taxis en Lourenzá (5). Parada de taxis en Lourenzá. Taxistas para desplazamientos a nivel local, nacional e internacional. Taxi 24 horas. Rutas turísticas, excursiones, traslados a aeropuertos y estaciones. Servicios para empresas, bodas o entierros. En Lourenzá hay 5 empresas de Taxis...
These companies will also advertise themselves via flyers ( to be found in albergues or pinned to a tree).
All the best with your preparations and Buen Camino.