There are likely two issue at hand. When you have multiple people in a conversation, it increases the load on your brain as it tries to process a multiple voice conversation. This can cause some mental chaos and mental lock-up.
The frustration with word finding can also be tough.

Maybe you can get some of your family and friends to understand the technical description of your brain's struggles.

The two most common problems are how your brain filters information and sensory stimulation and how it gates or directs the flow of information.

Filtering causes the information to over-load the brain with stimulation. Your brain will need to filter out voices so you can focus on and process a single voice. This excess information causes a sort of traffic jam in your brain. When you are with a group, you can just say that your brain struggles to filter out the voice you want to listen to from the rest of the sounds.

The gating of information is a traffic cop like system. It directs the flow of information to the proper area. It is part of the memory search system. You may need the word bathroom but your mouth wants to say basket. It can be like getting files mixed up in a file cabinet. You pull the file you think you need and inside is the wrong papers. Think of it as your brain sends the wrong word to you mouth. Or, it open the wrong door looking for the word bathroom and instead finds the word basket.

I still do this daily. I can tell you many of the letters of the word or name I am trying to remember but usually miss the most important letters. Yesterday, I was trying to remember the name Tracy at a 4th of July barbeque. I kept coming up with manes with combinations of a, c, r and y but the T never came to mind. Sandy, Cindy, Casey, etc. Like I just typed manes when I meant to type names.

If they don't understand, you can not make them understand. They need to accept what you tell them. Nobody would ever fake PCS just to get attention. It is much more of a problem inside our minds that they will ever observe from the outside.

Hope this helps.

My best to you.