I googled it and this was the result
A femboy is someone under 30 years who is biologically male that presents themselves in a (very) feminine manner, through their behaviour and physical appearance, or in a manner that would traditionally be regarded as feminine or effeminate
I understand that you meant the best but pleas don’t try and correct me on something when you know very little on the subject yourself
and I believe the term you are looking for is trans-Mac (a trans person that present masculine) or trans-fem (a trans person who presents feminine) or maybe you are thinking ftm (female to male) or mtf (male to female)
I hope you take this in a positive way and know more than why you used to on the subject thanks you have a good day!