I am constantly amazed at all these threads asking if you are too big for your ponies - If it isn't struggling to carry you, who cares? Do you really care that much about looks?
I ride Mounted Games, so it is the norm to see combinations like this -
That pony is an absolute rocket, loves his job, and doesn't struggle under any of the riders.
The only restriction we have in games is that if the pony is 12.2h or under, the rider must way 60kg or less.
Ponies are stronger than most give them credit for - I love ponies and will never stop riding them. For games and gaming, smaller means better agility.