Is it possible to learn how to read really early (really quickly), but not be smart?

When I was about 4 years old, my dad taught me how to read, and i caught on really well (not comprehension, but actuall words). I have always had some trouble with math. The doctor put me on ritalin when i was 6, because i had attention problems, and did not "follow directions well." In 5th grade, my grades were AMAZING, but in 7th grade things got harder. My depression/bipolar was partly to blame, i suppose for decreased ability to learn. I am pretty much cured, but i pick up on things so slowly that it is frustrating! I am an extremely slow reader, and during my whole life (even when my grades were good), it was hard for me to read and remember/understand what i read. I finish tests so slowly, and am ALWAYS the last one finishing. Now it seems like whenever i read, the info slips out, and there is no way i can write a plot summary or composition w/o Cliff Notes or Wikipedia (i have always been this way). I do NOT daydream at all in math cl, but i always need the teacher to clarify things! i am a junior in high school, and i used to be in honors cles, until it became wayy too overwhelming. Am i not smart, but just an early mental bloomer? I am ambidextorous (meaning i use both my right and left hand), so you can get a better idea about how my brain works. Peace x0x!