Hi charlie27. Know that you are not alone in finding fine motor skills to be particularly impacted by RA. We have quite a few articles from our contributors on the topic. One of my favorites is this one from Daniel on how his hands often seem to betray and fight him: https://rheumatoidarthritis.net/living/hand-weakness/.
Educating people about RA is, in many ways, a much more difficult issue. It is important to be one's own advocate, but it is also true that this is easier said than done - and many in the community note that often educating others can become exhausting.
On your particular issue, my wife, Kelly (who is a contributor here), thought that maybe a direct medical explanation might be of use. She explained it to others by noting that RA impacts the joints and the areas needed for fine motor skills, like the hands, actually utilize many more joints. Thus, there are a lot more points where, in any given moment, RA can cause a problem. Of course, I don't know if this explanation will work for you, but I can tell you that people here understand and that this community is here for you. Best, Richard (RheumatoidArthritis.net Team)