My rescued labrador

Hi! Welcome to the forum! Miley is beautiful! She looks all Lab to me. Labradors aren't supposed to be huge like you often see (mine is 100lbs and is way too big, he is a rescue). Females are generally supposed to be on the smaller side and 55-70lbs grown. And anyway, does it matter how big she is or will be? You love her no matter what her adult size is.

She's definitely on the small side for a Lab.  It's impossible to tell if she's pure bred and if she was found scrounging, the rescue has no way to know either.  Labs being so popular, you will see a huge range of sizes that don't conform to the breed standard.  I've known full bred Labs not much bigger than Miley.  Pocket rockets. lol   She is beautiful. :)

Aaww, what a pretty girl!  She could easily pass for a pure bred Lab.  At 4 1/2 months my Caleb was 30.5 pounds (yep, I have his records right in front of me.  LOL) .  He's matured to 65 pounds (at the minimum weight wise for a male).  And about 22 inches tall.  In general, at 6 months, they're close to adult size, but aren't done growing yet.  By a year old, you'll have a better idea of how tall she'll be (she could still grow some in height after her first birthday).  She'll start filling out during her second year.  Keep in mind, tho, that those are general statements- some lines aren't done filling out until they're 3!  And, like Jackie said- Labs aren't supposed to be huge.  Below is the part of the AKC breed standard regarding size. 

Size, Proportion and Substance
Size--The height at the withers for a dog is 22½ to 24½ inches; for a bitch is 21½ to 23½ inches. Any variance greater than ½ inch above or below these heights is a disqualification. Approximate weight of dogs and bitches in working condition: dogs 65 to 80 pounds; bitches 55 to 70 pounds.

 Thanks for the replies. I don't really care one way or another if Miley is purebred or not, I love her so stinking much already. Miley is definitely going to be my little pocket rocket! I'm stealing that phrase too, btw!!!