I know the feeling, despite getting three A's at AS, my careers organiser teacher suggested I look towards 'point based' unis, nothing wrong with them- but she couldn't get the deal I was aiming high.
Anyways, sometimes if you have poor KS2 (this sounds so irrelevant) but you are put into secondary school with those results and expectations. So the targets you have till year 9 are reflective of tests you take in year 6. Then you're year 9 SATS make up your GCSE targets and sometimes, they still take into account the KS2 tests dependant on the system.
So, that could be a reason why you're teachers aren't putting you up there.
To look smart- I suggest, ugh I'm going to hate saying this but, BBC English, glasses (might help), and preppy clothes and even associate yourself with 'smart people' if you really really want to be seen that way.