Thyroid confusion

Hi everyone. So I'm currently 20 weeks pregnant and was seeing a reproductive endocrinologist who released me to my ob/gyn at 12 weeks. My RE (reproductive endocrinologist) put me on synthroid for slightly elevated TSH at 3.4. At 9 weeks it went down to 1.9, and at 19 weeks it was 2.26. However, I'm just now learning about free T3 and T4 levels and I'm a little confused because I'm not sure if my endo checked those hormone levels as well. So far I've only had my TSH levels monitored throughout my pregnancy. Should I be getting T4 and T3 checked as well or is my TSH a good indicator that everything is in check? I hope this makes sense, I'm very new to all of this hypothyroidism stuff and am trying to protect myself and my baby. Thanks in advance for any insight!