If I can feel my thyroid a bit enlarged is this an overactive or underactive thyroid?

Enlarged thryoid can mean under or overactive thyroid. If you are gaining weight, feeling sluggish, or feel cold often, it is probably underactive. If you feel anxious, sweaty, or have been losing weight, it may be overactive. Underactive thyroid slows metabolism down, overactive speeds it up. Either way, you need to consult a doctor for a definite diagnosis.