i've seen a lot of things on how to sound feminine and most of it is complete pile of rubbish. you have a set of vocal cords and they are tuned for a certain range. stress them and they sound like it and you get what you are experiencing now. you're first step is to realize that women have a wide range to their voices, from very high to some actually in the bass range with quite a few in the tenor bracket. embrace that fact. women form their words in a different part of the throat than guys do, look for vids on that difference and you will have a very natural sounding female tenor voice in a relatively short amount of time.
i have a gg friend that has a tenor voice and it is lovely. on the phone guys swoon over it and in person she it a delight. nobody ever says: hey, your deep voice makes you sound like a guy. it doesn't. she speaks like a girl in her dialect and how she forms her words.
also notice phrasing women use, a sure give away is to listen to a person's speech pattern to see if they are guy or gal--when you talk with a guy dialect, then people will start thinking she's a he, no matter how convincing you look.
