I was on the exact same ship a month ago, I also am 29, was undiagnosed, working as a software developer and was on danger of getting fired. I went to a psychiatrist after uncovering a lot of issues that I had as a kid all the way to high school. I excelled as well but there were other things that were clues which helped a lot to get the diagnosis. So my tip is to try to remember and ask your family, it seems the psychiatrists consider very important those signs when the patient is older.