T3 can be useful in small amounts. For instance, you could cut a 25mcg tablet into 8 pieces and take one piece every few hours. This low dose shouldn't affect your body's natural T3 production or prompt your liver to metabolize it faster. You might not notice any difference in how you feel, but technically, you'll have the support of extra T3.
Another option might be using small amounts of coconut oil throughout the day, which could be more beneficial for you.