Ok, so I have a wedding in a couple of weeks and here's my dilemma:
My sister's a bridesmaid, and she's wearing a demin skirt. I want to look cute, because you never know who I'll run into

but don't want to upstage the bridal party. I'm not sure what the bride is wearing. Plus, I think it's in poor taste to not dress up for a wedding. The wedding is in a church, and the reception is in the social hall, so I'm guessing no alcohol.
What should I wear???
PS-I didn't get my own invitation to this wedding either, but I'm ok with that.