Honestly? You're young. Take a breath- relax. Ask yourself- Are you completely, 100% happy with her? Would you be happy, or happier, with her not in your life? Here's the thing, if you're not invested 100% into a relationship, it's not healthy for you or for her to continue. If you think your life would be better and you would be perfectly fine without her, then it's better not to drag it along.
But keep in mind, at 16, you have many more years to decide who you're going to live your life with. At this age, you have time to slow down and have fun with her for a while before you know if you should be with her forever. That's what dating is for, it's basically a test to decide if that is or isn't the right partner for you.
Do what makes you happy and best of luck!