I'm only going to be 5' 2"?

Okay, I'm going to be 13 in Aug, and I'm 4' 11"/5' 0''. My dad is 6' 1" and my mom is 5' 6''. My dad's family is kind of tall I think, and my mom's family was kind of short. I added up my height using my mom and dad's height, and it said I was going to be 5' 11''. But, I heard from a few online doctors and people, about adding up your height from when you were 2 years old (They all say it works, so I gave it a try), I pulled out our old VHS tapes from when I was around 1 1/2-3 years old. I was an extreme midget back then! I estimated my height from back then, added it up 2X times, and it said I'm only going to be about 5' 2''! Is this true?! What do you think?