Hey Christine! Getting rich darks in graphite usually comes down to layering and the tooth of the paper, not just using softer pencils. Even a 9B won’t get darker if the paper’s tooth is already filled that’s when graphite starts to look shiny or seems to fade. Try building your values gradually in light layers, for example working from HB → 4B → 6B → 8B instead of jumping straight to 9B. Also avoid heavy blending early on, because it can flatten the tooth and make it harder for the paper to hold more graphite. A helpful trick is to increase pressure slightly only in the final layers, and work on paper with a bit of texture so it can grip more graphite.
You’re definitely not alone with this getting strong darks is something many artists struggle with at first, but once you get comfortable with layering it becomes much easier. Keep going and don’t lose hope we all are here to guide an help each other 👍

thanks