Overcommitment?

So here's the deal, my gf and I have been dating about 6 months now, she's 15 and I am 14 turning 15. This girl is the most amazing, sweetest, prettiest girl u'll ever meet, and i really like her. I can be myself around her and she makes me happy and there is no way i want to lose her. However, just a few days ago my mother was asking how serious it was getting. It's not reallly getting dangerously serious, or at least that's wat i thought, When responding to my mother's text of "So do u think you are gonna marry her?" I obviously gave her a very mom answer, "I'm 14 i don't want to overcommit to marraige at this age." That text is true, i'm too young to know wat i want for the rest of my life. Unfortuantly for me, that text was accidentally sent to my gf as apposed to my mother, and she got really bent out of shape about it. She said things like 'i guess its ok if u dont think that.' I guess my point is, I wanna be with her, but i really dont want to commit that much to her.