Do I need to be concerned with a consistent resting heart rate of 100? Blood pressure is usually 110/80.

Possibly. I see you are on synthroid (thyroxine). You may need your thyroid level checked. Also, if your anxiety (on xanax) is not controlled, that can result in a fast heartbeat. Generally, this may cause problems in the future so you should get it checked out.
Probably not. At your young age, a heart rate of 100 is not likely to be dangerous. It usually means that there is some other metabolic condition or non-cardiac problem. Common conditions causing an elevated resting heart rate would be anemia or thyroid hormone excess. A graded exercise and fitness program might help to decrease your heart rate.