1300 sf is big assuming the number doesn’t include garage floor space. Average house size was under 1000 sf in the early 1970s. If you have another 9000 sf of outdoor space for hobbies, entertaining, and play, five people and a few mongrels living in 1300 sf is a non-issue.
With 1300 sf, you end up using 450 sf for four bedrooms (one master), 100 sf for kitchen, another 150 sf for 1.5 baths, 300 sf for living/dining, 100 sf for hallways, 200 sf for enclosed porch/family room. Perfectly adequate for everyone to have their own private space as long as you have modest expectations. But a 10×10′ bedroom seems positively huge to a child.