Well when you create your bio make her a female. Or you could draw her without horns, antlers, or nubs?
My doe Ayaki has antlers, it's all about how you roleplay and create the character. You have endless possibilities.

Ahh, I see. What are the smaller deer I have seen that resemble does, but larger in build than fawns?

those might be the adult deer with the small spell cast upon them. I'm guessing here, seeing that my deer are still fawn but i know that there is a perma fawn spell.

Osmotious, you can stay as a fawn by checking the 'play as fawn' box in your game's 'display' menu. It's not a spell.