Let me do some math here, 18 minus 1 1/2 equals 16 1/2 and she is 16, minus 1 1/2... well I get the point. Does anyone else?
Dear Kyle, welcome to the forum. After answering to another poster with similar heartaches and posting this one, I hope that you did not expect this relationship to be the one and only in your life.
Dating is about learning how to cope and grow with another person and getting closer than anyone else before. From these relationships we get a taste of emotional capabilities that are new and it is hard to give these up. You don't have to give anything up, you just have to accept these as part of your life and accept that she is going through these growing pains as well. All we can expect in these relationships is happiness, pain, or apathy.
At your age, you both will probably meet and love a lot more people during your journey and I hope that with most of them, you'll have fond memories of the time that you had together. That's what makes us human.
Respect her wishes as you'd want her to respect your wishes if you wanted space, and believe me there will be times when you need time to collect yourself and the young lady will be as confused as you are now.
Keep in touch and read more from those that are going through what you are, it helps to know that you are not alone.
Good luck.

Life would be so boring without learning all about it.