You're not a bridesmaid

I need a little help. I'm 38 and newly engaged. We want a small bridal party. I've always said I'll only have my sister (48 y/o) and her daughter, my niece (15 y/o) as maid of honour and bridesmaid, respectively. My fiancé has a 5 y/o niece who he'd like me to have as flower girl.

My fiancé is having two best men and no ushers, except for my 11 y/o nephew.
I have a lot of good close friends. Lots of girls I'll call my best friend, but no real single best best friend. Whomever I don't ask would be disappointed if asked other friends. So my plan has always been to not ask friends.
Only, I messed up. About a year ago, 8 months before getting engaged, I had a text conversation with a friend. A close friend. She said she'd dreamt of me getting married to my fiance and that she was there doing a reading. I had replied "as my bridesmaid". I regretted it immediately. And now I feel beholden to it. If I go ahead and ask her, I'll have to ask about 7 other girls and I just don't want hoardes of bridesmaids. I don't even want anyone doing readings.I know she is waiting to be asked as the other day she read this conversation out to me, from her phone, as I sat in front of her. She'd said you have to let me do a reading. You promised. I said, did I? And she said yes. Then read the convo, stopping before I had said "as a bridesmaid". But we both know what was said. When she asks for updates on the wedding, I just say we haven't sorted anything yet. Still deciding on venue. Which isn't true as we have decided on our wedding party. I just don't know how to tell her she's not bridesmaid. I don't see her often - maybe once a month - so is texting about this ok? I'm currently burying my head in the sand. Advice please x thank you x