I agree; my step-grandchildren call me a version of grandmother and kind of get mixed up with their other two grandmothers (our daughter-in-law is adopted so her mother isn't the "real" grandmother either). What one is called is not as important as the relationship and the child will sort that out as he gets older. No way to control what he calls your boyfriend when he's at his mother's house anyway; just what he calls your boyfriend when he's at yours.