Hi Paula!
Such a difficult question, so just a few thoughts to throw into the mix.
1) Is getting a Compostela at the end important to you? If so, you'll probably have to walk 5 days on the same stage ending in Santiago to achieve the 100km required (you can take rest days, but can't take transport along the 100km). The Compostela will be written out in your name, but you could get it dedicated to your son. See this thread.
frequently-asked-questions/topic6838.html
2) Is it important to you to walk the
Camino Frances? Other routes may be worth considering. They will be quieter and you might meet fewer people, but could be more contemplative. I'm thinking, for example of the Camino Ingles (approx 5 days Ferrol-Santiago and over 100kms), and the Camino Finisterre (approx 4 days Santiago-Finisterre). Other people could advise on routes such as the Portuguese. The advantage of doing it this way is that you may spend less time travelling between points by bus and may be able to fly both into and out of Santiago at the start/end.
3) Do you think you'll ever go back to do other sections? If not, maybe consider the types of landscape and experience that will help your contemplation. Mountains or plains? Lots of company or just a bit? You'll lose the friends you've made each time you move on, so if forming friendships is important, bear that in mind.
These are just a few ideas, and I'm sure you'll get many others. As always an element of 'go with the flow' will serve you well. If your plans go by the wayside after day one you're having a good Camino!
Best of luck, and keep us posted! Buen Camino!