This is a tough one. Typically you would need a "control solution" with a known pH in the narrow range of your test strips, but it is surprisingly difficult to come up with a reliable solution in a home setting without buying a specific calibration solution from a lab supply like Fisher Scientific. (rejecting that solution)
Distilled water is only pH 7 the instant it is made, so with no buffering capability, its pH will swing wildly from just the CO2 in the air. Unless you have a milligram scale and lab-grade materials, even common household products will vary wildly based on brand, formulation… even the water and precise measurements you'll need to turn it into standard solution. (rejecting that solution)
Other homemade "standard solutions" (e.g. calcium hydroxide used by reef aquarium experts) are too far outside your range to be useful. Hardware stores (in the lawn and garden section) have bottles of 7.0 buffer solution for calibrating pH meters for testing soil. I'll assume you don't have any of that on hand so… (rejecting that solution)
So what's left?
Well… oddly enough — human blood.
Turns out that human blood has a tightly regulated pH of 7.35 - 7.45. If it goes 0.2 either up or down you die. Human blood only maintains that pH for a very short time outside the body, so measure quickly.
How's that for a life hack?