Please, please, please do NOT get pregnant without your husband fully in agreement. If you require him to accept the responsibility, inconvenience, expense, risk, work, and sheer exhaustion of raising an additional child, but without enthusiasm or without acknowledging his needs, that will not bode well for the future of your family.
What if your husband were pressuring you to have another child you don't want? Even adoption, without the physical discomforts of pregnancy and labor, would put tremendous demands on you. Would it be fair to force anyone into that situation?
You've gotten some wise advise from other mamas. Choose to notice how many blessings already surround you, and you'll discover that every moment of your life is complete. And please don't make the mistake of revealing to your one child (or any additional children you might eventually have), that they are somehow not "enough" for you. That's a painful burden for a child to bear, and kids often end up feeling at fault when their parents are unhappy for any reason.
Living in joy and gratitude bears fruit. A change in your "wanting" as the focus of your childrearing could eventually bring a change in your husband's resistance. But don't do it for that. Do it for the well-being of yourself and your family. Model for your child what being an emotionally healthy grownup looks like! It is your choice, and I hope you will be able to find for yourself that this is true.
Blessings to your union and your beautiful baby.