I had the same feelings, as I think many teen girls do. I did a lot of babysitting and playing with other people's children. Having a child as a teenager pretty much locks down your potential, and distracts you from succeeding to the fullest. Worth the wait!
As someone who was married at 18 with a baby on the way, it is difficult, even if you are not single at the time. This is not something to be rushed. After having four children, and with currently one on the way, 23 was honestly the perfect age for me to have children, even though at that time I already had two of them.
The point I am trying to make is, there is time later on. Right now, enjoy the life you have, go to school, think about what you would like to do for your education and employment opportunities in life. Babies are wonderful beings, and they bring much joy, but they also grow, have many needs, some needs you do not know how to fulfill, if there are special needs, how to support them if there are therapies or special education needed. Then there is daycare, diapers, formula or breastfeeding, so many things that go into parenting, that when we think we want a baby, we really want to love and attention and cuteness that a baby has to offer. We forget about all of the needs, and other items and attention a child needs.
I waited years, while having children, but was able to get my degree. Let me tell you this, getting a bachelor's and then a master's and raising four children as a single mother is no easy task.