Were you not offered the option to transfer purchased from your iPad to iTunes? Also, without having the iPad connected to iTunes, go to iTunes preferences on your computer and select devices from the menu at the top. Make sure to check the box next to "Prevent iPods, iPhones, and iPads from syncing automatically" the next time you connect to iTunes you should see the pop up asking to transfer purchases. Agree to that and after the transfer is complete, you can safely sync with iTunes and backup your iPad. There should be no need to restore your iPad.
In answer to your question about restoring without a backup, you would indeed lose everything on your iPad. Items purchased from iTunes can be re-downloaded from the purchased list but everything else would be lost.