Wiccan at church?

Don't fight the situation.
Leave yourself open to the positive energy which (may)reside
in both the congregation and the edifice itself.
Certainly not all of what you hear and experience during
these ceremonies is negative, and, being relaxed and
accepting, you can glean from the sermons that which is
helpful to you and simply disregard the rest.
Your family loves you, and many of the people withing
that congregation will emanate kindness and caring as
well.
Use this time to reflect, and feel safe.

Look up Trinitarian Wicca. It should solve a few problems for you guys

You have a perfect opportunity to learn to act like a Child. I wouldn't advise you to be explicit about your endeavors. Actually, just think of church as "Hog Warts."