Start taking prenatal vitamins as soon as you can. Don't stress out about those things. Our bodies are made to carry a child and if it is meant to be it is. I think that worry is always in the back of each expecting mom. I'm 24 and 17 weeks pregnant and haven't had any problems. Just eat well, take vitamins, and take it easy. Get into a doctor as soon as possible. After your first consultation you will feel much better. You will get all of your questions and worries answered and out of the way. Good luck! I'm sure everything will be just fine. Congratulations!
I think it all depends on if your body is ready. You really cant forsee a miscarriage and you cant really determine why you have one. Dont stress though, im 22 yrs old and 8 weeks pregnant and was really concerned about the same thing. But if youre going to keep it then stay healthy and your body will know if its ready