One thing you'll have to remember is that you don't necessarily get a half and half cross. She might be a 50X50 cross, or she could be 50X25/25, 25X25X25X25, or any variant, although you can tell Lab is the dominant breed.
If she's 10-12 weeks old, as she appears, judging by the comparison to the chair, she could easily end up being a moderately large dog (60-80 pounds). Those legs are very sturdy.