Well, everyone's different, but what do you mean, "too much"? Making you tired? Hungry or hot?
The body normally produces about 25mcg a day. So 12.5 may get you to about normal with the additive effect, but just barely.
There's a lot of argument on the half-life...between 10 hours and 1.5 days. So, I'd find a way to do ED dosing to be stable as possible.
Done this with Letro...To get a smaller dose, try this:
1)Smash it up in a spoon or other device,
2)Then cut it up it into as many equal lines as you desire, say, 3 roughly equal lines of about 8.33mcg each)
3)Then eat one "line".
And maybe
4)explain to your wife why you have 2 or 3 lines of powder lined up on a smooth surface, and try to convince her it's Thyroid