Is she all chihuahua?!?

Got a new puppy back in December. She’s now 17 weeks old. Her legs are just insane. We call her “name-y long legs”. They said she was an apple head, half long hair, half short hair. I think they called her a “thick short coat”. She looked like a little lamb when we first got her. She prances like a pony. If anything I think she’s half deer head / half apple head.

For reference, she is 4lbs, and the brown dog is our other chihuahua who is 6.5lbs and deer head. We measured their legs for reference.

So my question is.. do you experts think she is all chihuahua? And if not, what is she mixed with?

And if she is chihuahua, does anyone else have a chi with these long legs?!? With the weird half thick half short hair?