Getting fixed

Is there any single mommies that have gotten fixed at a young age? I'm 13 weeks with my 2nd baby and 23 years old, I'm wanting to get my tubes tied after this little one arrives but a lot of people are saying I may need to wait because I'm under 25 and not married but I really dont think my body can handle another pregnancy and delivery. I'm looking at my financial and overall health going into the decision. Both my babies were unplanned but greatly loved little miracles conceived while on birth control so I'm afraid it could happen again later on but I have a bad back and the epi from my first born gives me some issues and I'm fearful this 2nd time will make it worse. I am planning on speaking with my dr about it as my due date gets closer but I'm wanting some input from others as well