Replying to I think my shop doesnt know how to tell what size ski i need.

heres the story, i am currently rriding 157 chronic wides and they come up to aboutmy nose or a tiny bit more. now, these skis are going to die soon so ima pick up a pair nextt month for summer camp and next year. this ski will only be park so true center. i asked for a 171 invader and they said that it would be a huge change and way to big. for reference im like 5'6 and maybe 110 pounds. since the ski will be true center i think it would be the right size for camp and next year considering im still growing. they told me to go with the 161 invader for camp and next year...i personally think theyre dumbasses but lets hear what u guys have to say about this.