little babies but still considering adoption

I am 49 and have small children with my husband. Before we were lucky enough to have these children via medical miracle, we were and still are considering foreign adoption. We have thought so much about it. has anyone young bio children, but still want to adopt but has questions like? would it be hard to adopt a child older than your bio children? should we wait till our little ones are older (but then we would be older too!) we thought about Foster to adopt but again, we have small children in the house and it might be complicated. Any way, interested to hear if any had situations like this? We are not sure, one way or the other at this point, but in my heart I do feel a drive to adopt so I feel I should explore that!