Bellatrix is half human and while she is proud to be a member of the horde and so also proud to be an orc inasmuch as she is, she is nevertheless not ashamed of her human heritage.

In fact, Bellatrix is not ashamed of anything.  She may have been born without a conscience.  It's not that she's actively evil necessarily, it's just that she doesn't care.

She presents a strange figure.  At five feet three inches tall and 180 pounds, she is below average for a half orc female.  She carries a drum which she made from the skin of the first enemy she killed when she was twelve years old.  She has stopped carrying the traditional orcish double bladed axe, partly because she is swifter than she is strong but more because she carries a lot of nasty little tricks instead, just because she can.  What she uses, more often than not, is a sling, a dagger, or even a cosh... or terror.

So yes, she is small, and from behind could be mistaken for somebody's chattel, but hear that drum play, watch her dance of death, or even gaze into her eyes and her enemies shiver in fear.  The only one she cares for is her twin sister Gora, the Twin of Strength.