If your going to ise it, I think you'd be happier with the results from a t3 cycle if you get yourself a little leaner first. It's my opinion that, at your bodyfat level, getting leaner without the drug is exactly what you need to do anyway.
That being said, 12.5-15 mics is usually expected to not be catabolic (and may in fact increase protein synthesis) and causes minimal thyroid supression.