@Erk: One thing to remember is that tinnitus is a symptom, not a disease. So, for example, you may have ringing in your ears (which is what tinnitus is) as a symptom of hearing loss. Or an overexcited auditory nerve. Or any number of other underlying causes.
So yes, if you perceive a "ringing" or hissing or other sound in your ears, you have tinnitus. The important thing to figure out is what's the cause, if you can. Sometimes, the cause can never be determined. But other times, it is due to something that needs medical attention (like a tumor) or can be fixed in some way (like a jaw misalignment).
You say you have migraines. And also, you have had tinnitus since you were very young -- which suggests to me that it probably is not from noise exposure.
If your tinnitus bothers you: You should have testing done by an otoneurologist -- a neurologist who specializes in the auditory system and its connection to the nervous system. But if your tinnitus doesn't bother you -- it's a symptom, like I said, so it cant' hurt you --and you feel your migraines are being properly treated, maybe you can just ignore it. I have a former student who just graduated medical school. Like you, she has had tinnitus since she was a child and has learned to live with it. But it wouldn't hurt to try to figure out what is going on here.
I hope you will talk to your parents about this. Good luck.