Karen:
This a great thing to do with your daughter. Have you visited Stockholm previously? If so, you are aware it is a pricey destination (but Oslo and Norway are even pricier). Lodging in Stockholm can be expensive by most US city standards. If you spend all 6 days in Stockholm uou might want to check on AirBnB to see if you could get a place for a week, just make certain it is a short walk to the Metro (the T).
While Stockholm is a unique and picturesque city, I'm not certain you need 6 full days there. This may a bit off-the-wall, but what about 2 full days and a third partial-day in Stockholm, the afternoon of the third day take an overnight ferry to Helsinki or Tallinn, on the 4th day and that evening and most of the fifth day visit in Helsinki or Tallinn. On the afternoon of the fifth day take the overnight ferry back to Stockholm, on the sixth day fly back home. This itinerary would have to be modified depending on when your flight arrives and departs Stockholm, but it’s a thought. If you would opt for such a journey, you might want to stay at a hotel in Stockholm (rather than the BnB noted earlier) to avoid travel on the T with luggage (to/from the ferry).
My wife and I took the overnight ferry from Oslo to Copenhagen and it was very pleasant. From a base in Stockholm you would experience n the archipelago in the evening and the morning on the return trip. You would see Tallinn or Helsinki from the water as well as walking (and, in Helsinki, using the Tram) experience the city for a partial day, one night and most of the next day.