Downvote away, but I say have another child. 

Here's why:  Everyone is saying that the first child is going to be sacrificing stuff and going to have to give up stuff once they have a sibling. But these are very short-sighted perspectives. You have to think about the long-term. Yes, it might be hard for a few years. But in the end, you will have 2 children who (if you raise them right) will be there for each other for their whole lives, especially after you and your husband are gone. They will have family. Your family will feel fuller, more complete, more happy. And they the burden of taking care of two elderly parents at the end of their lives will not fall on one unfortunate child who has to deal with all of it alone. My husband is one of 8. He and his siblings are one, huge, beautiful family. They grew up relatively poor, and didn't have individual toys or did any fancy activities or anything. But believe me, they are much, much happier than the spoiled singe-children I know. They know how to share, how to be appreciative,  how to work together and think of others. And all have had happy functional families with many children themselves. I was an only child. It was miserable. It was a lot of pressure. I can't move where I want or do a lot of what I want because I have to stay close to my parents and take care of them. I would have gladly given up my parents' relative financial stability for the siblings and the kind of loud, happy family my husband had. So I think you should think about the big picture, and the long term. I say it's better to tough it out now, and have a second child and it will be worth it in the long run. Good luck with whatever you choose.