is the armour light because my character is a bosmer or i have a higher light armour skill than heavy armour ? or because it was designed to be light armour and ifit was designed to be light armour ... why ? it looks like it should of been heavy

Its whatever your better at. I beleive.

At the point when you start to receive your armour, whatever is the highest skill (heavy or light) is the armour you get.

It's because your Light Armour skill is higher than your Heavy Armour skill