My girl was estimated between 2-4, her teeth are similar in wear, and she doesn’t play with toys at all, and was never given bones or anything resembling a treat, just had some kibble tossed her way once every other day or so. Basically, she didn’t have any reason to have wear on her teeth like she did, and when my regular vet sold her practice and retired, the next vet said agreed with me and was leaning more to the older end of the 2-4 years. This will be her 9th year if I go by the 4yrs when I got her. Best 5 years of my life!
You’ve got a gorgeous girl, enjoy her no matter the age! Some dogs bred or raised poorly will still outlive their healthier bred counterparts. Don’t let the age question slow either of you down, she will let you know when it is time to slow down.