I'm not 14 years old but still fairly young (18 years old, in 2nd year university). I do have schizophrenia as well as some other disorders, and for the most part, I'm doing pretty well in university. I see you're linking IQ scores to intelligence, which is somewhat of a problem. Gardener suggested various types of intelligence, ranging from logical/mathematical to social to musical and many more. IQ scores only tend to measure the logical, spatial and reading/comprehension forms of intelligence. I believe it was Mozart who, according to my psychology professor, at an early age could write more music notes than he could letters, so if he were to take an IQ test at that time, he'd probably be considered mentally retarded when in fact, he was a musical genius.
Even with the illness, people can be extremely successful. Last time I did an IQ test I didn't get in the 140 range, actually only around 120-125.

If you are interested in mathematics and such, practicing various spatial, logic and math problems would probably help.

Listening to non-intellectual music, as far as I know won't affect your IQ unless you try to make it, such as purposely act, dress and dumb down yourself to be like the artists.

To give you an example of what someone with IQ of 120-125 is doing right now, I'm taking these courses (F = this semester, S = next semester):

- Medical Pharmacology (F)
- Ecology (F)
- Cell & Molecular Biology (F)
- Physiology of Plants and Animals (F)
- Organic Chemistry I (F)
- Perception (F)
- Organic Chemistry II (S)
- Human anatomy and physiology (S)
- Genetics (S)
- Abnormal Psychology (S)
- Neuropsychology (S)

In 1st year, it was (Y = full credit):

- Physical Chemistry (Y)
- Calculus (Y)
- Physics (Y)
- English (Y)
- Evolution (F)
- Diversity of Organisms (S)

Granted, there are harder course than what I'm taking, as well as easier courses. However, this is merely meant to show, a person with a decent IQ score can indeed achieve something (my grades are/were pretty good, with the lowest being about 72% in English).

I will say this, if you focus too much on other things, such as contemplating what possible sources could lower your IQ score, you're essentially wasting your time. There is a possibility it could affect you, and a possibility it couldn't, there are no definites.

As for confusing the piss out of people, who cares? If they need a dictionary when they travel with you, so be it. I've confused many people, some smarter, some dumber than myself using various terminology, such as occluding zonulae to sp^3 hybridization.

On a last note, you said your father's mental abuse makes you feel you're not intelligent. There's an old saying, which goes "You have to dress for success". Give yourself confidence because if you go into a test with your head down, belittling yourself, telling yourself how you're so stupid and will fail, there's a higher chance that you will. You could take what your father is saying as something to overcome and prove him wrong. He calls you stupid, so do your school test, and get a high score. Stupid people usually don't get high scores (assuming they don't cheat or something).

My parents for the most part were abusive, both physically and mentally, as well as being bullied around always at schools didn't help for many many years. That could be part of my problems but I try to use that in a good way. Whenever I remember those times, I get pretty angry (and I do have a very short temper), so I try to fuel myself at times off anger, hatred, etc... . May not work for you but try to use what's kicking you down to pick yourself up and move on.