To respond to your comment "Still trying to see how we can go to Bijagos for only 2 or 3 days without having to pay a fortune to a private boat company" the only way to link with the Islands is using public ferry tranportation leaving Bissau everyfriday morning to Bubaque and returning every sunday morning or afternoon, depending on the tides. You can see the schedule at http://www.consulmarbissau.com/en/boat-timetable-bissau-bijagos-bubaque-bolama-enxude
Once there, you can visit the Bubaque island, which is perhaps enough for one full day (saturday). If you want to go elsewhere, like Orango Natural Park to see Hypos or Canhabaque to do some interesting trekking, you would need a private motot boat, which I would say you do not pay a fortune, but usually a fare rate taking into account maintenance and petrol costs for boats in that part of the world, where everythiing needs to be imported.
Good luck with your trip.