To be honest, I think that the military lifestyle would be absolutely toxic for an INFP, especially the Marines and Army. Navy, Air Force, and Coast Guard have much less domineering approaches to service. Fi is a very personally oriented worldview, and there is a whole lot of Te and Fe in the military that will constantly 'attack' one's Fi. Also, there is little room for possibilities, as the military is often a 'one answer' institution that strongly discourages alternatives which would be toxic to Ne. I think that the FPs of any kind, and especially the NFPs, would have the hardest time with the military of all the types.
However, you're not done developing RL, and the military might be a great way to forge yourself into the man you want to be, by forcing you to adapt into the person they will make you.