Thanks for tagging me club! Welcome to the club Dragon_God. I do my best to be supportive of all new plaers. The Separa'Shan are a Star Army something, not my something, so if you can think of improvements please feel free to mention them.
First thing is the Separa'Shan did not have space travel of any kind until YE 29. As that is when first contact was made. Given his family's anti-factional views, it is entirely possible he grew up in the Jungle away from other Separa'Shan.
To me, it makes sense that around YE 29-30ish they could have left with their own ship (though that would probably entail a closer connection to someone in the outside world) which would be around the time he turns 10. However, as others have mentioned they don't take their humanoid form until they are around 14. That said, if you can figure out a creative way for him to have helped out, have at it. There is a long tradtion on Essia of children growing up in the jungle and hunting for themselves. You may be able to work with that.
I also might move the start of his military training later.
Also he'll know some variation on the Separa'Shan language.
If I were to rework his backstory, I'd probably have his parents be traveling traders on Essia. Once he was old enough, he helped his family by hunting in the jungles while they traveled. Once he turned fourteen, he started helping them out in earnest and learning to fight from the guards of his parents caravan. Everything after that is pretty much the same.
Overall, I like it and can't wait to see him in play!