Is your goal to go to university in the US? Or is it to go to university in the US only if you can go to Harvard or Stanford? It is definitely possible for you to get into a good university here if you continue to do well in school, but that university may not be Harvard or Stanford.
And if your goal is simply to become a physician, it will be easier and cheaper for you to do this in Sweden. Plenty of foreign doctors come to the US to do training so that they can practice medicine here.