I got pregnant with our only child at 34, and turned 35 a month after she was born. We figured on only have one, and some complications I had post-partum (blood clots and a pulmonary embolism not being the least of them) sealed the deal for us.
It sounds like you have at least a couple more years to think about it, but also think about your reasons for wanting another. You did not mention how many kids you have now, or their ages, but depending on where they are at, once they are old enough to be out of diapers and in preschool part-time, or regular school full-time, you might not want to start all over again with a newborn. I don't know, everyone is different. But for me and my husband, 1 was good enough for us and we decided to "quit while we were ahead."
One mom I know had her first child at 36, her 2nd at 40, and her 3rd at 43. So it is possible, but one thing she didn't count on was how tired she felt at 47 having to deal with a 4 year old, a 7 year old and an 11 year old. Another thing to consider.