I think the bigger question is how can you begin to live your life differently so you don't keep making bad decisions.
Yes, there are lots of women in your situation who struggling with the consequences of poor decision making. But you didn't get here by yourself, there were men also making those poor decisions.
Your first paragraph is pretty illuminating - I'm dating a really great man but it's not likely he'll love me. Really great men don't repeatedly have sex with, and impregnate, women they don't love.
Your sisters probably weren't "lucky" in arranging their lives "perfect" as you say, but rather, they learned how to make good decisions and by and large thought through their life steps.
At this point, are you open to their advice? In the future, when you are dating some guy are you open to listening to whether your family likes him?
The thing is, this amount of difficulty didn't happen in a day, or with one error - it's a lifestyle of doing things you probably knew at the time (or were told) were not a good idea.
I don't mean to sound harsh - your life must be very difficult. But you're the captain of your ship, and you've got 4 (and maybe 5) children who are relying on you to give them a good start and a good role model, and so far that hasn't happened. It would be very helpful if you could find someone you trust, and listen when they give you advice about mistakes you are about to make.