Advice on joining the military?

I am currently 16 years old, and plan to join the military right out of high school. I was mostly thinking Army or Marines. I eventually want to join the SOCom of wich ever force I choose. I always loved guns, and am very skilled with using them as well. I am also in great physical shape to join. I just can't make my mind up, Marines or Army. I WANT to be in combat. Please no one say that I don't. I was thinking Marine Force Recon, unitl I found out that they don't really see much combat. Then I was thinking Army Special Forces, but then I found out that they just train indigenous personnel in guerrilla operations and provide medical care. Perhaps the NAVY SEALs? But I never really wanted to be on ships. Can I join lets say the Army and then join the SOCom of another force like Marines? Thanks for reading this long question.