The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, says a person with an intellectual disability has both:

• Problems with intellectual functioning (reasoning, problem-solving, planning, abstract thinking, judgment, academic learning, and learning from experience). Intellectual functioning is often measured by IQ tests which give scores. Intellectual disability is usually no higher than the range of 65 to 75 points.
• Problems with adaptive functioning cause a failure to meet developmental and sociocultural standards for personal independence and social responsibility. Without support, problems will limit functioning in one or more activities of daily life (communication, social participation, and independent living, in many settings, such as home, work, school, and community).^[1]American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Intellectual Disability, Diagnostic Criteria. This document will be referred to as the … Continue reading

These problems with functioning must exist during the developmental period of life, which means during childhood or teenage years. Under the Lanterman Act, a person must have these problems before age 18.^[2]Section 4512(a). 

If the regional center’s evaluation says you do not have an intellectual disability, you should ask another expert. An expert can say if your condition qualifies as an intellectual disability.