Hi Jonathan,
I’m probably not the best person to ask about Medium stuff such as increasing caption length under photos. Frankly I have no idea. Sorry.

But I can expand on ‘supportive community’ comment I made. As well as writing a piece on the follow me idea I did a search on other pieces by people who are doing the same thing. I commented on their pieces and clapped etc. I also went to other articles that interested me, commented and clapped. I also followed as many people as possible, providing they had a some interest to me. That’s all I did. In roughly 24 hours I had gained the extra 40 followers to get me over the 100 mark. However I notice that you haven’t published that many articles yet. That will have an effect on the amount of followers you attract. People who attract many followers and readers publish almost daily sometimes more. I try to publish between 3-5 weekly, but I should probably do more.
I couldn’t see your purple background. On my device, at least, your colour background does not differ from the norm. On my device this is black.
Best wishes, nigel