I'm sorry about your son's recent diagnosis. Like you, we have no family history either.
My son's bloodwork was sent to Baylor when he was diagnosed. They sequenced the whole gene and detected his specific mutation - deletion of exon 51. When they tested me for carrier status soon after they sent it to the same lab and ran the same test looking for the same mutation. I came back negative as a carrier. I don't think my insurance covered it or if they did it was only 50%. I still plan on getting my girls tested. Even if you are negative you could be a germline carrier (a % of your eggs are affected). What %? They don't know and I was thrown out a 7% figure.