With the low level of T4, your TSH levels should have been high if you are hypothyroid. You may see an endocrinologist
who would look into the current picture and advice properly. You may need to be tested for anti-thyroid antibodies
before prescribing any treatment. Hypothyroidism
may cause low-birth weight
and preterm babies and can be safely treated during pregnancy. Please discuss with your doctor for further management. Wish you good health.