I think that the thing to think about is why it is important to you to have that gifted label. I do know kids for whom reading came easily and early and who are not gifted per WISC IQ scores. I also know some whose IQ scores are erratic or which don't fully represent their intelligence due to learning disabilities. I would not really want to be one of the latter.
If you are seeing areas where you struggle in life (it sounds like you had a concern due to your presenting with the concern of dyscalculia), then it is worth considering what types of accommodations would help you overcome those weaknesses. I'm assuming that you are a recent high school grad given that you listed your age as 18 on another of your threads. If you are needing accommodations in college that you did not have in high school, it would be worth seeking out the help of the college's counseling services early on and seeing whether they see reason from your current test scores to give you accommodations such as extra time on tests.
That aside, it sounds like you have a need to explain your differences from your family and that "gifted" might be a way to do that in your mind. If it isn't giftedness, it doesn't mean that you don't have reason to feel alienated (it sounds like you might feel that way) or that you aren't a wonderful person in your own right even if your family hasn't accepted you.
