Getting my tubes tied?...

So I'm on my second pregnancy. I have a 23 month old boy, and I am currently 24 weeks pregnant with twin boys. My husband has a 8 year old boy that lives with his mom (which we only get to see him every other weekend (Friday night,Saturday and have him back by Sunday night) so by August, we will be a family of 6! I'm pretty young (24) husband is (30). My doctor had asked me if I wanted to tie my tubes after having my twins. Right away I said no. My husband wants me to, but it's not like he's making me do it or either forcing it. He just suggest that I get it done, while they do the c section (since my insurance would pay for it) I honestly don't know why I don't get it done. I just don't feel "ready" what if I want more kids later.? Idk. My husband asks me if its because we don't have a girl, but honestly I don't know what stops me from desciding not to go thru with the procedure. Any advice or opinions anyone can give me?