Gidday Sadie 243 and thanks for your post.
I have a similar situation with three main groups of friends who are linked to activities I do. One is cycling, one is radio controlled sailing and the third is stand up paddling. Each group has a quite different personality.
Recently I had a major birthday and invited all three groups. Of course I worried like you about how they would get on.
My wife came up with a trick - everyone was given a large name tag and had to write on it what their primary interest in life was - just one word. Well it wasn't half successful! Lots of them said family, others said being kind, others said reading books, some said cooking, others keeping fit, and so on. Very unexpected really.
And that was the catalyst to start all sorts of conversations between the groups.
So it went from me feeling nervous about mixing different groups, to lots of people chatting about their interest in life. Later feedback to me was how interesting and varied my friends were!
I wouldn't worry about people judging you by your friends - that is going to happen anyway and is arguably a good thing! listen to the feedback and use it to make yourself a better person if that it what you feel you want to do.
It sounds like you have a likeable personality and a great boyfriend. Use that opportunity to deliberately mix friends at a cafe etc and see what happens! You may even want to ignite conversation by saying to the group how different your friends are and what can we find to talk about! Make it humorous and they will respond in ways you might not expect.
On the other hand, it might work to keep you different friends groups apart from each other, giving you the opportunity to stretch your mind it different directions with each group!
Anyway, I hope this might be of interest to you Sadie243 - I'm quite happy to see what you think!
And all the very best with managing your OCD.
Kind thoughts - The Bro