Your T3 and T4 can be low enough that you need medication and still show low but within normal limits.
You need to hold off on getting pregnant until you have explored the thyroid issue fully and understand why your TSH is off.
A full thyroid blood panel, including several antibody tests should be run. A palpation of your gland may or may not indicate the need for an ultrasound of the gland.
Persue this until you have a firm diagosis. A problem thyroid can raise havoc with you once you are pregnant. You need to have a handle on your health before that happens, or the pregnancy could go very badly.
Hi .. I am not too familiar but wanted to say hello and others will probably reply a bit later .. WELCOME!
Cheryl