I have stepchildren. They were grown when I married. I fully expect to have a Step-Grandchild. But if I don't, that would be ok too.
I have 6 grandchildren. I know 2 are step grandchildren but which ones??? My heart smiled the first time my new one called me Granny and wanted to show me his art work.
Like you, I married late, and it was the best thing I ever did to wait for the right one! I "inherited" two step-children who are a joy, and have a delightful step-grandchild. I feel I got the best of both sides! Hang in there, and may a lovely step-granchild come along for you to enjoy.