How do i know my mom is my real mom?

Answer 1

She, and others, have probably told you that she is your mother. If you don't believe her or them, you can have your DNA compared to hers. That is not cheap, but it is nearly definitive.

Answer 2

Look for similar traits, such as: hair, likes, dislikes, eye colour, etc. You could always see a doctor and ask to see your and your father's genes and ask if they are slightly similar.

Answer 3

A maternal DNA test is probably one of the surest ways of finding out whether your mother is your real or biological mother. A birth certificate is another way of finding out as well.