1st choir accompaniment

The truth says I'm not a very good accompanist. That's the past though. Accompanying my mum on the piano, a few singers and instrumentalist. It was hard. I tend to go my speed and the practicing and all. I just tend to stop or pause or make obvious mistakes.
Here I've been asked to accompany many of the major performance players at the con. For performance, competition, exams. I refused their offer though. I didn't wanna ruin their performance and I know there are better accompanist out there. I just don't have the confidence.
But yesterday it was more of a force to play with the church choir for the 1st time. It was like a little force last year to sing the solo part with them. I suppose I'm glad they did it. I had to sight read 2 pieces and it was going quite fast with the middle section of the piece always being the hardest part with large chords and notes spread apart. I must say, it wasn't that bad at all. Made mistakes that's for sure but I put in a few extra notes(my own), improvised(mostly when I'm lost) and just kept counting ;p It was fun to hear, count and play all the same time. Feeling the rhythm and just losing myself to the music. I didn't worry and wasn't nervous(that's new). I just played my best and waited till the rehearsals were finish.
Lost my voice by the end of the day talking(i can't stand being super quiet. it's just not me).
2 major choir performance coming up in 2 weeks time. Confident with the chamber choir but I still haven't looked at the pieces for big choir(chamber choir is helping out the big choir in their performance). I know I'm not suppose to sing or maybe just doing my practice singing lessons will do and might have to wear a sign saying "I'm not anti-social. I just can't talk"