Tubal Ligation

I have an almost 3 year old and I’m pregnant with my second child. I’m currently 7 weeks. I am 22 years old and I don’t want anymore children so I asked my doctor if I could get my tubes tied and she said I had to be absolutely sure since I am so young and I need to make a decision by 20 weeks so I can sign some papers. I get pregnant so easily, and I don’t want to take my chances with another birth control. Has anyone else had their tubes tied at a young age? What were the side effects? How long have you been having sex now with zero protection and still haven’t gotten pregnant?