Not being able to absorb lactose due to the insufficient presence of the enzyme lactase, does not automatically mean that lactose intolerance symptoms will manifest when consuming lactose-containing products.
Recent studies have shown that, although about 70% of the world population does not produce sufficient lactase (the enzyme that breaks down lactose, making its components available for absorption) the symptoms of lactose intolerance may not necessary occur.
It has been shown that some lactose intolerant people can still drink a cup of milk with food and experience no side effects. Some studies found evidence that many lactose intolerant patients can drink 1-2 glasses of milk per day with no side effects. (1, 2)
Currently, lactose intolerance tests involve ingesting 50g of lactose (equivalent to 1 liter of cow’s milk) followed by the measurement of hydrogen in the breath.
However, such a large dose of lactose on its own, with no other nutrients, may cause mild symptoms even in healthy individuals. Even if these tests show that you are lactose intolerant it does not mean that you cannot tolerate some milk or other dairy products. (1)
NOTE: In cases of severe lactose intolerance (when your body produces very little lactase) symptoms occur after just a minimal amount of lactose intake. In such cases, it is safer to adopt a lactose free diet.
It will take some time to research and become accustomed to it, but after some weeks or months, it can be life transforming.