Am I selfish for not wanting another baby?

So I’m 33 going to be 34, and I have three kids, ages 13, 9, and 6. They are all in school, but my bf that I have been with for 15 years wants to have another one, and I really don’t. I think… they are all in school now, and I don’t want to have to do it all over again! I’ve also had all 3 of them through the c section …am I being selfish?