Be as healthy as possible. See your doc and follow their guidelines. Always put your baby first. And never let anyone pressure you into anything you're not comfortable with and never let anyone make you feel crappy for anything. No matter your age you can be a wonderful mother and always make the best choice for your family. Welcome to this amazing ride!
Sleep as much as possible because a baby will take up a lot of your time. Enjoy being 15 while you can because soon you will be a mommy and you are going to have to think for 2. I got pregnant at 16 and although my mom wasn't to happy I had her support, of course I chose to do things on my own because after all I Chose to have sex at a young age and get pregnant. All I can say is good luck, and if your parents offer u advice and help take it, just don't put to much responsibility on them..after all your the one that's gna be a mommy. Babies are precious trust me when you hold yours for the first time, the entire world around you is gonna disappear. Also you can start picking out baby names, if you know the gender then you should start buying what you need. Also try to get your babys daddy involved with all the baby stuff like ultrasounds so he to can feel connected to baby. Biggest advice I can give is fugure out about school because you should finish school so you and your baby can have a better life and future and also more importantly stock up on diapers cuz your gonna need them. :-) GOOD LUCK AND CONGRATS!!
See your doctor asap so they can confirm your pregnancy, estimate a due date, discuss your options, get you onto any required vitamins and schedule your upcoming appointments.
Eat healthy, don't smoke or drink alcohol, do some regular light exercise.