Is my tragus peircing infected?

As long as it's not red, painful, feeling hot, or discharging pus, then it's not infected. The bumps are most likely just scar tissue. They will probably get smaller with time, as with any scar. If you're really worried about it, go back and see the person who did the piercing or see a doctor and have it checked out. It doesn't sound like it's infected though.