The first time my wife and I ever performed with electronic amplification we had no idea what was going on. There was a knowledgeable tech at a fancy soundboard and people on stage to properly set up the equipment. We did a quick sound check as part of the setting up. At the end of the first number I asked the audience and the soundman, "Is it normal for me not to be able to hear my wife while we are performing this way?" The soundman immediately adjusted the monitors.

The point is, it took a while to get used to being plugged. I literally did not know what we should be worrying about (other than knowing the material). The first few times we performed using a sound system, I was so rattled that my brain would shut down and I would forget to do all the really obvious things. I once started playing and noticed that my dulcimer had a strange rattle I'd never heard before. I soldiered on and discovered at the end of the song that I had wedged a pick under the strings near the bridge and forgotten it. I now have a mental checklist that I walk through slowly and faithfully. Is my chair stable and am I comfortable (I usually perform sitting down)? Is everything I will need stable and within easy reach? Can I hear both my voice and my instrument? Can I hear both my wife's voice and her instrument? Is she still in tune? Am I still in tune? Etc. My advice: slow down, take deep breaths, don't forget to do the obvious, listen carefully, as soon as you notice a problem stop and fix it.