I feel trapped by my circumstances. Is there a story in the Sai Satcharita that shows how confinement can actually be a blessing?

Yes, the story of Amir Shakkar in Chapter 22 provides a powerful lesson on this. To cure his rheumatism, Baba commanded him to stay in the dilapidated Chavadi for nine months, even forbidding him from visiting the Masjid. Amir initially felt this was a prison. However, this apparent imprisonment turned into a great blessing. His location provided effortless, daily darshan of Baba and, on alternate nights when Baba stayed in the Chavadi, it led to intimate conversations after the devotees left. This shows that what seems like a restriction can be a path to rare companionship with Sai.