Is it normal that i have gotten stupider?

I think that I used to be smarter than I am. In my freshman year of high school I got the highest grade in my honours biology class. I only got one b in that class, and that was because I accidentaly wrote definitions for terms instead of examples on a test. My best friend once told me that I was the smartest person that he knew. Another person that I knew told one of my friends that I was so smart that it was scary. I had a 3.8 GPA through my first two years of high school. I once got an A on a maths final after staying up all night hanging out with my friends. I got first place in the Skills USA state web design competition, and I got 11th place in the nationals. I do not mean to brag. I am just trying to establish a baseline for comparison. my last two years of high school I got straight F's I had some psychological testing done, and I scored really low in almost all categories. My great grandmother recently told me when she was born and asked me how old she was, and I couldn't answer her. my mind just went blank. I am now 19 and I live in my dad's basement. I am a high school drop out with no job and no GED. Is this normal? I feel like I cannot ask my family because they will just lie and tell me how smart they think I am.