Tubal ligation

I’m turning 30 next month and currently pregnant with number 4. I’m planning to do ligation once i’ve given birth but it seems that my gynae is totally against it 😔 She said that i’m too young for ligation, don’t want me to regret in the future. She’s given us other birth control option but we prefer ligation for some reasons. Me and husband already discuss about this and we’ve already made up our mind 100%. What do we do now and how can we convince our gynae to let us get ligation?#advicepls