Registry frustration

So my shower is this Sunday, I’m expecting about 20 people to the shower, there’s a registry link on the invite, my list is not extravagant and there are many affordable things on it, but mostly it is a practical list of things we actually need. Out of all the people attending only 3 have actually purchased from it....I’m getting quite anxious thinking I’ll be receiving things I don’t want or need and I’ll have to go and scramble to exchange things. Sorry, just don’t really know what to do, I can’t just send an email out telling people to only buy from registry....