I have had a similar situation my self. I had an feeling that I might have AS but I did not want to tell anyone for the same reasons you don’t. I researched I and did all the tests on the net and every time they all said some thing like strong possibility you have AS. For a while it played on my mined eventually I talk myself to the doctor with out my parents knowing. I was referred to and educational physicists and diagnosed with AS. I tolled my family and once they where very supportive apart form my dad. Any way I felt much better getting it all sorted. I think you should do the same thing. Tell your brother. Maybe he will take you to see the doctor so you don’t have to go one your own. It could be a good why to strengthen you relationship ship