On small houses that you believe to be not too leaky, you should try using ring b or c. Using the fan in the open mode or with ring a is usually for larger houses and/or leakier ones.
You need to experiment a little, don't be afraid to. If you are using the blower door system from Energy Conservatory, they provide a very good/comprehensive manual with the system or even online on their website. Check it out.
It's just a simple small box of a house. Not that big and only one story, no nooks and crannies. If it has good windows and a good plaster or drywall job, and as you said laminated floors, and it lacks attic ventilation to code, then it is not surprising that it is relatively tight. Open up those gable vents and vent the attic to code, and I bet you will get a higher leakage number, but it might not be much more.
Small simple square salt box or cape cod type homes don't leak that much. Multi-story homes and homes with more complicated architecture leak a lot more.
If you do a good job on this house you will get it pretty tight so better plan for mechanical ventilation, and plan to upgrade any natural drafting combustion appliances.