That is normal (really), your hormones are out of control, but a good friend of mine felt the same way and intentionally got pregnant at 16. She then said 'holy shit what was I thinking' and promptly got an abortion. And although she never regretted the abortion, she suffered emotionally for a long time afterwards. Now, at 28, we are both pregnant, and although in my case this pregnancy was planned and wanted by both my fiance and I, let me tell you, it is no walk in the park. I am 12 weeks along and feel nothing but exhausted and fat. I weighed 113 pounds when I got pregnant and tipped the scales today at 126. Peeing all the time, feeling like a lethargic slug...ugh!
Anyway, sometimes you can trust your feelings, and sometimes you can't. Feeling like you want to be pregnant and have a baby is NORMAL, but be strong if you can, don't listen to this little voice in your head, and don't act on it. I think most girls who give birth in their teens would totally agree with that statement. And if you can be strong and resist the urge to have sex, I really think you'll thank yourself for it later. Children conceived in a loving, committed relationship will have fewer challenges in life -- it is a selfless gift to your future children if you can be patient.
You'll also thank yourself for waiting when you hear other girls complain that the boy they gave it up to left them, or cheated on them, they are worried about an STD, or have been branded as a slut, or feel dirty afterwards, or whatever.
I don't think you can make the feelings go away...but maybe you can redirect your attention elsewhere once they set in? Like on art or exercise (so then you won't want to be pregnant and lose your figure!) or something? It is a big challenge to confront these feelings, as there is no denying that they are very powerful and do indeed feel wonderful when the time is right, and I wish you the best of luck.