Sometimes the voice box, for whatever reason, does not grow very much in response to testosterone, or the voice box does grow but your voice remains high because you're not used to the size increase of the voice box so you unconsciously modify your voice to mold your voice box into the way it was before. This happens to cis guys too. They have all the usual secondary sex characteristics, but their voice retains a prepubescent sound. If the cause is the latter, voice therapy can help. I wouldn't be too worried about it. Eventually you will have a beard, etc. and you will have strong male gender cues that will overpower that. Whenever I encounter guys with a voice in the female pitch range (it's more common than you think!), I actually find that I tend mentally interpret their voice as lower than it actually is due to other male gender cues (beard, etc.)
ETA: Perfect example of this is actor Michael Cera. In terms of pitch, his voice falls into androynous range. However, when you see his face, he doesn't sound like a woman or prepubescent boy at all, he sounds like a grown man, just his voice is less deep compared to to other men. It's because of his intonations as well as other male gender cues. If you compare Michael Cera's voice to Miley Cyrus, you'd actually find Miley's voice is slightly lower than Michael's. However, they still both sound like their gender, and most people actually wouldn't notice that Miley's voice is slightly deeper until you point it out and play interviews of them side by side. It's all because of things like voice intonation as well as appearance that affect the perception of the gender of one's voice.