I don't think anyone can give you a definitive answer on this but I can show you some photos that might help you.
I remember when we first adopted ours we don't know where she came from, she'd been dumped to fend for herself. She weighed 9.1 lbs then. Everything I read said they grow slowly when they are on a natural diet. Our lawn is exactly what she needs, I don't feed her because I don't need to, she eats the lawn. I thought I have several years before she gets so big that I can't pick her up.
Yeah.. right.. after 2 years here I couldn't pick her up anymore.
This coming July will make it 5 years since we got her, she's around 70lbs now.

I have some photos I can show you. These are all torts that my vet has.
I'll do this in a couple of posts.
The first photo is the baby that was born this month at the age of 1 day:

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PHRatz