Tubes tied??

So me and my bf are pregnant with our second child and so happy but he feels that after this I should get my tubes tied but I want at least one more and he doesn't I'm so young I'm only 20 we talkes to my Dr and she said she's willing to do it if I want to but I really don't what If we break up and I wantore kids with another person and I can't I think it's only right that if I get my tubes tied he should have a vasectomy