I want a new lens, but idk nothing! :/ Help

Hi guys,

I'm new here

So, i have a nex 5n and i do like it, is really good for my style of life. I'm not a photographer, but i travel a lot and i take tons of pictures.

I use the nex because i walk all day when i travel and big/heavy cameras are a no deal for me at the end of the day.

Right now my nex are with kit lens 18-55. It's good, nice bokeh when zoomed, but i feel that i'm too "croppy"? I can't put all that i want or all that i'm seeing with my eyes in the picture. My brother told me that i need a Fisheye or wide angle.

Idk, i also like the portrait pictures.... i mean, i like to take pictures of people face when i walk ( so skater!!! that's why i think wide won't work for me, i don't want to jump in front some one to take a picture) So.. is there something for me?

i saw: 16mm28f - 50mm18f - 35mm18f... some sigma lens and zoom lens.

Witch one do you guys recommend me? I don't want to pay more than 600us for it.

some pictures... (i take more close up pictures, japanese girls )

Thanks!