You might be OK. ABigail at 6 months still wears a small HH and the fit is great and it is one of the first diapers that she fit into and she was less than 6 pounds when we brought her home from the hospital. One of them could habve benefited from a cross over tab but enough of the Aplix stuck on both sides to make the diaper work, its just that she had a little ridge of extra tab in the middle. But the other was just fine, just all the way closed. I don't kow the differene, but it couldn't hurt, huh? At least one.