pregnancy immediately after ?

has anyone gotten pregnant a few months after having a baby?

I think I might be pregnant again and my LO is 4 1/2 months old. I'm terrified. I am on birth control.

I want to keep it if I am, which I know will be very hard. but I have a loving, supporting family that helps tons, and my boyfriend's family is very supportive as well. has anyone else gone through this? any advice?