My TSH level is 0.745 and I'm taking 125mcg of levothyroxine. I'm always feeling tired. Is that normal?

Not normal, but. Fatigue is not "normal", but it is very common and can be caused by many medical and/or mental problems. If your thyroid level is normal (hopefully you're taking brand name replacement which is more reliable), they your fatigue isn't due to your thyroid. Start looking for other explanations.