*hug*
You are probably right. Especially if you are not in their physical presence much, they probably still think of you as your bio gender, remember you, etc. When you see them face to face, that's when it will likely all come rushing back again.
Has there ever been a dear friend in your childhood that you didn't see for some time, and suddenly when you saw them again they had changed dramatically? I imagine it would feel like that, to me, seeing one of my daughters transition "all at once". I'm out to my mother, who is supportive and loving, but I've been wrestling with this, too, since she is at least 16 hours' drive away. To her, I'm still her son, when she thinks of me she probably thinks of me the way I look in the most recent picture, viewed through the lens of her perspective of the way I grew up. I know that it will be hard for her, when I transition fully, if I don't keep her in the loop gradually through pictures during HRT.
I still get wistful and sad when I see how tall my grandson has grown between visits...
*hug*
I think it will probably take time and many visits for them to accept the new you and begin to replace the picture of your male shell in their heads with the picture of the real you that you are revealing to the world now. You've been transgendered your whole life, but I would imagine they haven't known about it until comparatively recently.
Wishing you love, luck, joy and peace in your journey.