Auroramarianna,
You could absolutely go a bit lower if you wanted to go for a more natural sounding voice; to me, it does sound very young, and if your range is what I think it is, you could do even better than you are already. In that upper register, things sound strained, and I can't imagine that it isn't uncomfortable for you to speak that way. When the time comes and you want to go for a passable female voice, I would absolutely use a deeper, richer tone...when it comes to voice, a number different factors come into play: Cadence, pitch, timbere, and so on. Even though your voice is still much higher in pitch than most male voices, the flat quality of sound makes it feel artificial, and when you're trying to pass sounding natural is key. Try speaking from your chest, and using that (I'm going to assume) amazing range of yours while speaking...you have a great baseline to start from, and I'm sure you'll go very far with a bit of practice!
Best of luck,
Sasha