I'm one of those people that believes in "using ten words when one would do."
Oh this is me, too! As people see by the length of some of my posts. I just can't seem to get the words out right, to articulate.
My emails are always too formal, as well. I struggle to know how to word things.
When I'm writing on here, I try to write less formally that I used to. I also tend to change according to the thread...some threads are about informal topics so I will be more casual. On a serious topic I tend to be more formal because the subject required more considered word choices.
I have been through similar experiences of teasing and bullying. My parents called me "Grammar Queen" as a teen because I would insist on correcting their grammar during our conversations.
I still correct people on TV or radio but I've learnt not to do it in person except with my kids, who are learning. And occasionally with my husband, who is a teacher and accepts as good fun.
I've always been a mimic. So although my instinct is to speak formally and grammatically correctly, I tend to take some of the mannerisms of those to whom I'm speaking... Not all, mind you. Just some.
I think another reason I've become more adaptable is that I spent so long in Japan and that Japanese became my primary language and my English started to fall away. This meant that I effectively had to relearn a lot of English when I returned to Australia. I had forgotten a lot of longer words and my English had been "dumbed down" from years of speaking simplified sentences to non-native speakers. While in Japan I assimilated by learning slang and trying my best to speak like a native.
I understand exactly what you mean about translating what people say,
grommet. And about feeling dishonest with friends. While I have felt that, and do still occasionally, I've formed some new ideas about it. I've become more accepting of myself.
It all depends on how I perceive my behaviour: am I being dishonest, and lying to people, when I change my style of speech? That would suggest maliciousness on my part, a desire to deceive. No, that is most definitely NOT what I am doing. Rather, I'm being adaptable. I'm going with the flow. I'm giving the others in the conversation a degree of geniality, being gracious.
That may sound odd, but it works for me. In Japanese culture, it is important not to offend others; to use 立て前 (tatemae), "face", the official stance, the public face, as opposed to revealing one's private thoughts. The idea is that we are preserving harmony by doing this. The same is true in English speaking cultures, so it's not unique to Japan. I dare say many of us here have been reprimanded for being too honest.
Gah, long post again.
My point is, don't hate yourself for being adaptable. And don't hate yourself if you struggle to adapt. Adaptation is hard! And if you don't want to adapt, don't!
It is good to be yourself, and it is a skill to have a good command of language. If people mock you, shame on them. There is no fault on your part. Your brain is obviously more capable.
Australian human rights barrister Geoffrey Robertson is well known for his very formal manner of speaking.
In an interview I saw him explain that he had always spoken that way, even as a child.
Don't feel you have to change. And if you do change, accept it as part of your repertoire and as a sign of your higher evolution.
(My profuse apologies if this post is rambling... It's Sunday morning and my kids are in the other room playing on the Wii and shouting their heads off, the radio is on in the kitchen, roosters are crowing and the kid next door is wailing... I can't think straight but didn't want to set this post aside...)