Just a note for your understanding - you may already know this - calcium can't do its job inside the tortoise (making strong bones and shell) without either the real sun or an expensive UVB light. The UVB from either the sun or the UVB light, causes vitamin d3 to be made. Calcium needs that vitamin d3 in order to do its job. Without it, the calcium just gets excreted in the urine.
Keepergale and Yvonne are both correct. A 20 gallon long is not big enough. A baby that age needs a two foot by four foot enclosure indoors, three by six (at least) outdoors. Other than that, though, your animal looks to be in perfectly fine shape. Babies have some give in their shell well into the three year range. Once they pass that point, the keratin layers tend to increase exponentially, lending to the hardness that is typical of adults.