heavy filly

Hellooo, I just have a quick question. I have a 16 month old filly that I have been lunging lightly at a walk, trot 5-10 minutes. She seems to be real heavy in the front, and doesn't extend like she is supposed to. I was just wondering if this is an unblance issue as her hind end is 14.3 hh and her front is 13.3. Or if she is just lazy?

Thanks for any of your help regarding this! :)

Growing horses are going to be more clumsy in general and even more so if you are making them go in small circles like with lunging. Their bodies are contantly changing in size and shape and they have to constantly learn to control something that is "new".