What Breed Is My Dog?

I got this puppy about 2 weeks ago. First of all they told me he was 1 week old, he obviously wasn't, I figured he was around 3-4 weeks old. He's probably either 5 or 6 weeks now. (Don't judge, I know he's very little.) Now I've been told that he's a Pit Bull, but now I'm starting to think he's not.

Please help me identify his mixed breed ASAP. He's got green-ish dark brown hazel eyes and was born without a tail. Thank you so much. I would appreciate all your help.

By Joanabear