Don't feel so misjudged....you've completed your patrol, did your part in shielding off the enemy from resupplies.
The fact that no-one showed up in your grids means, that they are more likely to show up in others...so in fact, you're narrowing the chance of getting through the uboat-screen you help putting up.
Do your job...follow the orders.
Look at it this way: in RL, you would be glad you made it home safe again...and the end of the war got closer again too.
You will be an ace, regardless of resuls during this patrol in particular.
*edit*
sorry, I am VIIC/XXI-fan...
