There's almost never one 'right' answer. I suggest you wait until you're certain that this is the 'rightest' thing for your family. In my 60's now, I have, sadly, known a number of mothers and even more fathers who regretted having another child. Sometimes it's because the child had a severe handicap or a parent developed an unexpected health or employment problem, but sometimes it's simply because the parents realized there was not enough of their own time and energy to give each of their children. So that can happen.
And of course, maternal (AND paternal!) age increases not only on a baby's statistical chances of having a birth defect, but of older mothers experiencing problems during pregnancy and birth. While I do believe just about any problem presents an opportunity for growing character, some families just become overwhelmed. While I might be willing to take that risk for myself, it wouldn't feel fair to me to lay it on a yet-to-be-conceived child, or on other family members.
Finally, what I consider THE most important consideration for having ANY child is the state of the earth they will be living on. Overpopulation isn't talked about much these days, but it is a problem of truly shocking proportions. We are overwhelming the environment that supports us at astonishing rates, and even if most babies born today are able to live reasonably healthy and safe lives (some are not, already), their children's future will be even more grim. How fair is it to have all the babies we think we want now, if we are using up their futures simply by having them?
Yeah, I know that sounds dire. I've been around since the middle of last century, and have seen alarming and heartbreaking changes: to environment, social stresses, general crowding, public safety, competition for available resources, that most young moms today have no idea have already occurred. I chose to stop with one child because I was already aware of this in the 60's. It was a great choice for me, not because nature wasn't urging me to have more babies, but because it seemed the most right thing to do. I have never had a regret about this choice.