Help Me Find My Identity

For a while now, my aquatic turtle bro, Donatello, named after the famous Ninja Turtles, has been asking me to help him figure out his identity. As Donie keeps wading around in his fish tank, he keeps asking himself the question: "Who's my daddy?"

I dedicate this weekend to my turtle bro. Perhaps there's a turtle expert among us who can help figure out what Donie is. When he joined our family, he was supposed to be a Red Eared Slider--WRONG.

Take it bro!

Hello! I'm Donatello!

 I'm the kittens' favorite pastime.

 I just wish I knew what type of a turtle I am!

 I love to swim, but I have to come out of the water to breathe. I also have webbed toes.

 What do you guys think?

 That finger looks pretty friendly, and enormous. I'm only 4 inches long now, 

and I'm over 3 years old. I'm also hard headed, um, hard shelled.

 I love swimming in our outdoor pond, but unfortunately I can't stay out there. The raccoons would eat me, yikes!

 I took the plunge into the refreshing pond water. Yay!

I would appreciate any feedback as to what I am. 

Sincerely, 

Donatello, Twinkie's brother