Birth Control

Elena
So I'm stuck between a rock and a hard place... My mom is very religious and she will not allow me to get birth control from a doctor. I'm 16 and going to have my first baby in August. 
After I have my baby I want to get birth control that isn't super invasive, and doesn't have a lot of horrible side effects like extreme bleeding, weight gain etc... 
I don't know what I should get and how I should get it?