Don't worry about it! Slow growth as long as it's healthy growth is a good thing for a sulcata.
You do not want one to grow so fast that it becomes pyramided.
Slow steady growth: good, fast uneven growth: bad.
I finally got photos of my girl online. She was found when she was about 12 inches long. Horribly pyramided (I need to find her first day here photos & put them online) but this is her 3 years later. Her pyramids have diminished a lot in 3 years, she isn't perfect looking today but she really was much worse then.
Last month marked her 3rd year with us & even though she's better now, still this is what you DO NOT want to strive for:

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PHRatz