Wanting twins

Doctors suggest you shouldn't spend money on Ivf unless you have problems conceiving children. It can also allow you to conceive twins if it because a God given gift that it creates two embryos. It is costly and it may not give me twins or other multiples for the thousands of dollars it cost. I have a higher ability to conceive twins naturally because I'm biracial and my boyfriend soon to be fiancé is African American. They also say if you have a bmi of over 30 and a lot of other mambo jumbo. So if you have twins or are trying to become a mother or father of twins what's ur advice to me or what worked for you?