Are you insane? you are still a child yourself. Your parents are right to go mad. A baby is not a baby for more than a few months. It is a growing human being who, for the first few years of its life requires almost constant attention.
My friend (aged 35) has recently just had her first baby. Her and her long term partner (10 years) are frankly knackered. The baby sleeps for no more than 2 hours and then cries. It requires regular feeds and nappy changes, financially they are struggling despite being an affluent professional couple. This is a massive commitment.
But Ronie, what is more important is that you should live a little yourself. My oldest friend had a child at 15. Against the odds and with the sterling support of family and friends brought up a child who is well adjusted and sensible (despite training to be a lawyer!!). She admitted to me very candidly that if she had her time again she would not do it that way. She had no teenage years, no young adulthood. Her life revolved around her child. She has 3 girls now. All have been spoken to in extremely strict terms about safe sex, about the importance of a stable relationship and also about the fact that you need to live a little first.
Trust me Ronie, whatever you want, you need to put to one side. Your bf will not support you and by the sounds of it, your parents may not either. You will be entirely alone. How then will you cope?
I don't wish to be harsh, but "wanting a baby" at 15 is madness. I am 37 and would give my eye teeth for a child, but I am smart enough to know that I cannot do this alone and would be bringing a child into a house of chaos with someone who has an inability to cope with everyday life alone.