My contributions can't be as specific as some of the other girls, but off the top of my head I'd say your outfit almost works. I'd think a jacket would be more appropriate for a "professional" look. To me the outfit you described would be perfect business casual... But perhaps there are extenuating circumstances that could make this work in your setting? Style or material of cardigan, maybe? I'll let the other ladies take it from here and set me straight if need be.

I don't work in an office, but that sounds appropriate for a more casual office to me.

It sounds professional but on the Smart Casual side. You might check with your offices HR manager for guidelines on work place dress codes. If it is a small office, watch the boss (or another senior employee you admire) and try to mimic them until you are more confident.