i wanted to have a baby but i cant

Think about two questions, first, has you reached or even exceeded the right age? second, if you get married, will you still support your sister?? If both yes, just do as you like.

I think your mom wants you to take care your family. and she loveyour sister more than you. If "YES" then go and do whatever you wants to do. If you are a earning person then dont worry for other. Get marry with your guy and have a baby. But in mean time send some money to your mom so that she can take care of your sister. So you both can be happy.

If you get married, you still can financially support your sister, although, come March and she graduates, she should stop requiring your support. You should explore why you want a child so badly even if the father doesn't want to stay in your life. If you need somebody to love you, that's not a good reason to have a child. If you want a child, find a guy who will at least be there for support. Hands on and financially. Babies are expensive. Their upkeep is costly. Believe me, I have three kids. Figure out what the cost would be to clothes, diaper, and feed a baby/toddler/child. Can you do it? Alone? Only if you can should you have a child, everything else is unfair to the child. And btw, March is not that far away. And you are young. If you wait until your sister graduates and you still have the desire to have a child, and are financially sound enough to support it, then have this discussion with your boyfriend. Marriage and baby... It's a long time to think about it and really make up your mind with all the facts on hand, even if you have to go it alone. Good luck!

Don't be in a hurry. Having a child is not an easy dream- its complicated. Do not just think what your wants as in having a baby even outside the matrimony, you also think the future of your dream child. Do you want your child to be illegitimate and be annoyed later on by her or his friends? If your financial support to the study of your sister precluded you from marrying or having a family, then you just wait for some months, anyway she is going to gradutate this Mcoming March and get married at June. Your still young and tender to be in a hurry.