It's not that, it's just...well you're not doing yourself any favours, to be honest from the style of your posts I wouldn't have put you down as being 17.
Personally, I have a real problem with aggression, I'm also pretty sensitive and have a habit of completly over analysing and mis-interpretting what people say, therefore I make a point of following a couple of steps to make sure that my posts are fully thought out, age-appropriate and relevant. If I don't feel they are I apologise at the bottom of my posts and try not to qualify my apology with a "but".
The steps I follow are:
1) Type my post, off the top of my head, expressing my opinion/how I feel
2) Press advanced post and then re-read it, altering my spelling and grammer so it sounds like an intelligent 18year old wrote it.
3) Add smileys to make sure people realise when I'm joking
4) re-read (I occasionally sound a little tempramental and I wouldn't want to be offensive)
5) POST!!!
I know this seems a bit much, but if you are aware that sometimes your posts may be mis-interpretted or may seem a little aggressive or tactless, it's sensible to do something like this until it's habitual to be a little more polite, or to structure your sentances in a manner reflective of your age and educational status.
I apologise if this offends you and if anyone feels I should remove this then I will gladly.
God Bless, JEN