New Rule #6: The weight you lift is a tool to reach you goals. It is not a goal by itself. (The New Rules of Lifting, by Lou Schuler and Alwyn Cosgrove, p. 30).
That said - you work with the weights that enable you to complete the goal of your workout. From the sounds of it, you're doing just that. Don't worry, as you keep training those numbers will go up, just be patient.