Freya,
I don't know enough of your situation to advise you, but I would point you in a direction. There is a summer 3 week program in the US called 'CTY' - see here

http://cty.jhu.edu/intl/index.html

Students from all over the world attend the program - both in the US and some other countries. They also offer online classes.


So I think whatever you decide for the future, the first priority is to find teens that you can fully be yourself with. They do exist. Summer is a great time to find them. You may be able to find them online as well.
http://www.hoagiesgifted.org/on-line_support.htm#commun

As for the gradeskip idea - do you think that you could get As in the upper level classes? In the US, high school is where kids are not longer (totally) placed by age, and you may find that in a particular subject you can be placed with older children.

What are you expecting to do after high school? In Spain, what is the process for getting more education after high school if you want it? In the US, grades in high school matter so much - some gifted kids have to sacrifice high grades in order to be with older kids in classes they find interesting, some gifted kids take classes with older kids and still get the highest grades - smartness is part of the difference by not the largest part. Do you think you'll hurt or help your future chances by skipping?

What time does school finish? How much of the afternoon do you have availible? Some gifted kids take advantage of being underplaced by speeding through homework and using their time to work in science labs, or other projects. In the US, some kids take college level classes in subjects that interest them in the afternoons and evenings - is that possible where you live? online? http://ocw.mit.edu/index.htm

A far out suggestion is to apply to college, here's one in the US that specialises in girls who are ready for college at age 15 -
http://www.davidsongifted.org/db/Resources_id_10114.aspx
Keep talking to anyone at all who might have information that will lead you to the next right step for you.

Be sure to get in the habit of contacting anyone who has written an article or book that you find interesting with your thoughts and comments. And let us know how things are going, ok?

Love and More Love,
Grinity

Coaching available, at SchoolSuccessSolutions.com