It's really hard to just eye-ball your effectiveness in a group without a parser, especially against non-identical jobs. Sam's ability to WS more frequently and solo SC are big driving factors in their damage output. If you have concerns over your effectiveness as a DD I'd recommend using a parser for a few runs and see how your damage compares with others.
If you do find that you're not comfortable with your performance levels there's a few things you can do to improve. Make sure you are using at a minimum a TP set and a WS set. For my TP sets, I focus first on achieving 26% haste from gear (the cap) and then as much multi-attack traits as I can then accuracy. For my WS sets, first I focus on the primary stat modifier of the WS then I try to include +crit, multi-attack, or accuracy, based on the WS and the gear I have for the job.