I have 2 young Horsfields bought at same time in April. Was told they were about 9 months old. Both seem very healthy, eating well, very active, bright eyes & seem to have good bowel movements. Soak them every other day & diet is mainly weeds & flowers from garden all as per the tortoise table plant database. They're outside in the sunny weather & inside when not so good, in a decent set up with heat lamp & UV etc. temperatures all check out OK. One is growing well. Currently at 45g, the other literally hasn't grown at all & still weighs 26-27g which is only 1g more than when I got them.  Doesn't seem right to me & am contemplating taking it to a decent reptile vet, but it does seem perfectly happy & healthy. It has loads of energy & climbs about. Definitely eating as I sit & watch it. Any ideas? Should I be worried or will it just start growing when it's ready?

Yes I agree, get it checked out for parasites by a vet. Were they from a breeder or dealer ?

Re. "outside in sunny weather" - sun is not essential, torts like hazy conditions & sunshine with showers.

Let us know what happens,

Tom