Military + boyfriend = confusion

So I’ve been dating my boo for a year and a few weeks. I’ve decided after high school I’m going into the army. I’ve signed a five year contract and the whole first year will be basic and AIT school. I signed five years because of my job. But I’ve considered that my boo is going to do something while I’m away. We are only 18 and I do not want to get married nor have a child with him on my first enlistment. (That’s my moms rule and i’m sticking to it)

Over the past year we’ve broken up for a few days because he had sexted another girl. I broke up with him and well i sorta hooked up with a friend of mine but nothing happened other than oral. But I don’t know if it would be better to break up with him for the time being and he can still prove to me that he loves me or stay with him and worry. Im scared to think if I make the wrong choice I’ll lose him. Are we just going to be high school sweethearts or something more?