Hello & Welcome, Beaglebagel!

• two major relationship traumas
• feeling lost & worthless
• "...whatever I do does not seem important anymore. I can't concentrate on anything..."
• highly sensitive
• unrewarding work
• reluctant to open up
• feeling like a "loser"

We cannot diagnose, but I definitely see above causes and symptoms potentially indicating depression. You can take non-diagnostic screenings for depression and other illnesses on the Web. It would be best if you could see a professional, starting with a medical doctor to rule out possible illnesses that mimic depression (e.g. thyroid problems and anemia, etc.).

Again, welcome, and please keep posting!