A 34-year-old woman presents to the clinic for follow-up. At 27 gynecological screening showed an high TSH with a normal free T4 and high thyroid peroxidase (TPO) antibodies, so she was started on levothyroxine and continued it until delivery. She is now pregnant with her second child, her thyroid function tests show a higher TSH than previously with a normal free T4 and high TPO antibodies, and a thyroid scan demonstrates bilateral thyroid gland atrophy. What is the most likely diagnosis?