I have had a miscarriage. me and my boyfriend try for another baby, but it seems like i can't get pregnant anymore. why?

Many possibilities: I'm sorry for your loss. We need more specific details in order to give you a better answer. Well, at least i do. Bottom line, if you're having difficulty getting pregnant (infertility is defined as trying w/o success for >12mo), then it's time to go see your reproductive endocrinologist. In the meantime, while you're trying, start taking prenatal vitamins to minimize risk for neural tube defects.

Pregnancy: Keep trying. May take up to one year to get pregnant. If still not conceiving seek medical help.

Miscarriage: There are several possibilities and the answers can only be given to you by your gynecologist after an examination.