Choc Lab / Rottie?/ Shepard? mix

Question
We have a wonderful little girl that is a Choc Lab / Rottie?/ Shepard? mix. Forgive the question marks, but she is an SPCA rescue and the mix seems to rather heavily debated. I have two questions.
1- Is there a good way to judge her age? We were told she was 2- 2.5 months old when we adopted her, which from our experience seemed about right. We have had her for a bit over 2 months and her behavior would seem to suggest a younger dog then 5-5.5 months. She has grown allot, from around 12 pounds to around 45pounds.

2- I am aware of the standard waist/ribs measurement for health and weight, but I understand these can very a bit for some of the more muscular breeds such as the Rotts. As I stated above her mix is bit unknown. Is there any good way to judge the weight of a mix like this? She was around 12 pounds at her adoption and is now 45 pounds. She doesn't over eat like we were warned labs do, but that seems big for a lab.

Answer
Hello, If she is this heavy and only under 6 months old she is deffintly ccrossed with a large dog such as a rotty as these can get 90-110 pounds at maturity my labrador retreiver wasnt this heavy at that age she is full grown at 75 pounds now. And it isnt forver a question mark I reciently saw in a magazine I bought a few weeks a go...dog fancy that there are now DNA blood tests that can tell you what's in the mix!  I am not sure if its fully perfected yet or what areas its avalible in but it is intresting none the less.If you can feel her ribs without poking really deep for them and cant see them she is of a good weight. Most dogs have a waist even a good weight rotty will have some waist an overweight rotty has no waist and looks like one long square lol Labrador rtereivers and german shepards have defiened waists. Also Labrador reterivers do eat alot there life callnig is to eat everything in sight...labs are known to tip trash cans and eat the contents, rip open garbage bags and do the same, sit and beg for table scraps, eat any crumb that is dropped, clean there food bowls every time and lick your plates clean if you leave them unatended! This is from personal experiance my lab wants to eat everything and was overweight awhile back since she was also free fed I have changed that last year to all my dogs being fed twice daily a shedualed amount. Large breed dogs take 1 1/2 to 2 years to fully grow inside and out, the dog should be full grown in height at 12/14 months and fully filled in by 2 years.